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Sample records for structure type c6cr23

  1. Formation of M23C6-type precipitates and chromium-depleted zones in austenite stainless steel

    International Nuclear Information System (INIS)

    Kaneko, Kenji; Fukunaga, Tatsuya; Yamada, Kazuhiro; Nakada, Nobuo; Kikuchi, Masao; Saghi, Zineb; Barnard, Jon S.; Midgley, Paul A.

    2011-01-01

    Graphical abstract: Precipitate formation during the in situ annealing experiment at 650 o C. -- Formation of M 23 C 6 carbides and chromium-depleted zones in commercially available type 304L stainless steel were investigated by in situ transmission electron microscopy and analytical transmission electron microscopy. It was found that each individual small M 23 C 6 carbide starts to grow with a clear orientation relationship with the matrix, and film-like carbide was subsequently observed at the interfaces with asymmetric Cr-depleted zones. From these experimental results, a model describing the precipitation of M 23 C 6 and the formation of the Cr-depleted zone was proposed.

  2. Ion irradiation-induced precipitation of Cr23C6 at dislocation loops in austenitic steel

    International Nuclear Information System (INIS)

    Jin, Shuoxue; Guo, Liping; Luo, Fengfeng; Yao, Zhongwen; Ma, Shuli; Tang, Rui

    2013-01-01

    The irradiation-induced precipitates in argon ion-irradiated austenitic stainless steel at 550 °C were examined via transmission electron microscopy. The selected-area electron diffraction patterns of precipitates indicated unambiguously that the precipitates were Cr 23 C 6 carbides. It was observed directly for the first time that irradiation-induced Cr 23 C 6 precipitates formed at dislocation loops in austenitic stainless steel, and coarsened with increasing irradiation dose.

  3. M23C6 carbides and Cr2N nitrides in aged duplex stainless steel: A SEM, TEM and FIB tomography investigation.

    Science.gov (United States)

    Maetz, J-Y; Douillard, T; Cazottes, S; Verdu, C; Kléber, X

    2016-05-01

    The precipitation evolution during ageing of a 2101 lean duplex stainless steel was investigated, revealing that the precipitate type and morphology depends on the nature of the grain boundary. Triangular M23C6 carbides precipitate only at γ/δ interfaces and rod-like Cr2N nitrides precipitate at both γ/δ and δ/δ interfaces. After 15min of ageing, the M23C6 size no longer evolves, whereas that of the Cr2N continues to evolve. For Cr2N, the morphology is maintained at γ/δ interfaces, whereas percolation occurs to form a continuous layer at δ/δ interfaces. By combining 2D and 3D characterisation at the nanoscale using transmission electron microscopy (TEM) and focused ion beam (FIB) tomography, a complete description of the precipitation evolution was obtained, including the composition, crystallographic structure, orientation relationship with the matrix phases, location, morphology, size and volume fraction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. New type of M23C6 carbide precipitation in an austenitic stainless steel containing niobium

    International Nuclear Information System (INIS)

    Terao, Nobuzo; Sasmal, B.

    1981-01-01

    An electron microscopic study has been made of precipitation in an austenitic stainless steel, 16Cr-16Ni-0.8Nb-1.8Mo-0.06C. Attention has been focused on structural changes which take place during long ageing treatments, extended up to 14.4 Ms (4000 h). In addition to the wellknown chromium rich M 23 C 6 carbides, which appear, together with NbC, from the beginning of the precipitation treatment at 1073 K, a new plate-like morphology of M 23 C 6 carbide precipitation was observed after long ageing treatments. These M 23 C 6 carbide plates were formed on (110) planes in regions near pre-existing undissolved NbC particles and their edges were bounded by (111) planes of the fcc alloy matrix. It is suggested that this unexpected process might be favoured by the stresses produced around the undissolved NbC particles. (author)

  5. Cascades in model steels: The effect of cementite (Fe3C) and Cr23C6 particles on short-term crystal damage

    Science.gov (United States)

    Henriksson, K. O. E.

    2015-06-01

    Ferritic stainless steel can be modeled as an iron matrix containing precipitates of cementite (Fe3C) and Cr23C6. When used in nuclear power production the steels in the vicinity of the core start to accumulate damage due to neutrons. The role of the afore-mentioned carbides in this process is not well understood. In order to clarify the situation bulk cascades created by primary recoils in model steels have been carried out in the present work. Investigated configurations consisted of bulk ferrite containing spherical particles (diameter of 4 nm) of either (1) Fe3C or (2) Cr23C6. Primary recoils were initiated at different distances from the inclusions, with recoil energies varying between 100 eV and 1 keV. Results for the number of point defects such as vacancies and antisites are presented. These findings indicate that defects are also remaining when cascades are started outside the carbide inclusions. The work uses a recently developed Abell-Brenner-Tersoff potential for the Fe-Cr-C system.

  6. Effect of Cr content on the SHS reaction of Cr-Ti-C system

    International Nuclear Information System (INIS)

    Zhang, W.N.; Wang, H.Y.; Wang, P.J.; Zhang, J.; He, L.; Jiang, Q.C.

    2008-01-01

    The effect of Cr content on the self-propagating high temperature synthesis (SHS) reaction of Cr-Ti-C system has been investigated in this research. The thermodynamics calculation indicates that the TiC possesses higher thermodynamic stability than the Cr 23 C 6 , Cr 7 C 3 and Cr 3 C 2 phases, and the formation of TiC is the most exothermic. Additionally, the adiabatic combustion temperature (T ad ) decreases with the increase of Cr content except for the phase transition regions. The XRD result shows that the type of products synthesized by SHS changes that a higher Cr content corresponds to higher chromium carbide. When Cr content is 10 wt.%, only solid solution (Ti,Cr)C ss is formed in the products. When Cr content increases to 20 wt.%, besides (Ti,Cr)C ss , the Cr 7 C 3 phase is also detected. With the Cr content further increasing to 30 and 40 wt.%, the products consist of (Ti,Cr)C ss , Cr 23 C 6 , Cr 7 C 3 and Cr, and therefore, much higher chromium carbide is synthesized. When Cr content reaches 50 wt.%, however, the Cr 7 C 3 disappears and the final products become (Ti,Cr)C ss , Cr 23 C 6 and Cr. Moreover, when Cr content increases from 10 to 20 wt.%, the lattice parameter of (Ti,Cr)C ss decreases, while it increases when the Cr content ranges from 20 to 50 wt.%. Furthermore, the microstructure shows that the TiC particulate size decreases from ∼8 to ∼2 μm with the increase of Cr content from 10 to 50 wt.%, and the morphology shape of TiC particulate becomes more and more spherical

  7. Effect of carbon content on solidification behaviors and morphological characteristics of the constituent phases in Cr-Fe-C alloys

    International Nuclear Information System (INIS)

    Lin, Chi-Ming; Lai, Hsuan-Han; Kuo, Jui-Chao; Wu, Weite

    2011-01-01

    A combination of transmission electron microscopy, electron backscatter diffraction and wavelength dispersive spectrum has been used to identify crystal structure, grain boundary characteristic and chemical composition of the constituent phases in Cr-Fe-C alloys with three different carbon concentrations. Depending on the three different carbon concentrations, the solidification structures are found to consist of primary α-phase and [α + (Cr,Fe) 23 C 6 ] eutectic in Cr-18.4Fe-2.3 C alloy; primary (Cr,Fe) 23 C 6 and [α + (Cr,Fe) 23 C 6 ] eutectic in Cr-24.5Fe-3.8 C alloy and primary (Cr,Fe) 7 C 3 and [α + (Cr,Fe) 7 C 3 ] eutectic in Cr-21.1Fe-5.9 C alloy, respectively. The grain boundary analysis is useful to understand growth mechanism of the primary phase. The morphologies of primary (Cr,Fe) 23 C 6 and (Cr,Fe) 7 C 3 carbides are faceted structures with polygonal shapes, different from primary α-phase with dendritic shape. The primary (Cr,Fe) 23 C 6 and (Cr,Fe) 7 C 3 carbides with strong texture exist a single crystal structure and contain a slight low angle boundary, resulting in the polygonal growth mechanism. Nevertheless, the primary α-phase with relative random orientation exhibits a polycrystalline structure and comprises a massive high-angle boundary, caused by the dendritic growth mechanism. - Highlights: ► Microstructures of the as-clad Cr-based alloys are characterized by TEM. ► EBSD technique has been use to characterize the grain boundary of primary phases. ► We examine transitions in morphology about the primary phases. ► Morphologies of primary carbides are polygonal different from primary α-phase. ► Solidification structures rely on C concentrations in Cr-Fe-C alloy.

  8. The mercury chromates Hg6Cr2O9 and Hg6Cr2O10-Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

    International Nuclear Information System (INIS)

    Weil, Matthias; Stoeger, Berthold

    2006-01-01

    The basic mercury(I) chromate(VI), Hg 6 Cr 2 O 9 (=2Hg 2 CrO 4 .Hg 2 O), has been obtained under hydrothermal conditions (200deg. C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K 2 Cr 2 O 7 . Hydrothermal treatment of microcrystalline Hg 6 Cr 2 O 9 in demineralised water at 200deg. C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg 6 Cr 2 O 10 (=2Hg 2 CrO 4 .2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg 6 Cr 2 O 9 : space group P2 1 2 1 2 1 , Z=4, a=7.3573(12), b=8.0336(13), c=20.281(3)A, 3492 structure factors, 109 parameters, R[F 2 >2σ(F 2 )]=0.0371, wR(F 2 all)=0.0517; Hg 6 Cr 2 O 10 : space group Pca2 1 , Z=4, a=11.4745(15), b=9.4359(12), c=10.3517(14)A, 3249 structure factors, 114 parameters, R[F 2 >2σ(F 2 )]=0.0398, wR(F 2 all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg 6 Cr 2 O 9 contains three different Hg 2 2+ dumbbells, whereas Hg 6 Cr 2 O 10 contains two different Hg 2 2+ dumbbells and two Hg 2+ cations. The Hg I -Hg I distances are characteristic and range between 2.5031(15) and 2.5286(9)A. All Hg 2 2+ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg 2+ cations is nearly linear with two tightly bonded O atoms at distances around 2.07A. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66A. Upon heating at temperatures above 385deg. C, Hg 6 Cr 2 O 9 decomposes in a four-step mechanism with Cr 2 O 3 as the end-product at temperatures above 620 deg. C

  9. Coprecipitation of M23C6 and MC type carbide under the influence of irradiation

    International Nuclear Information System (INIS)

    Kesternich, W.; Nandedkar, R.V.

    1991-01-01

    After high-temperature neutron irradiation of 1.4970 type steel, M 23 C 6 precipitation was observed in the matrix. This precipitate phase was found only at grain boundaries after thermal treatments. A unique feature of this irradiation-modified phase formation was that the M 23 C 6 precipitates nucleated at the surfaces of pre-existing MC type carbides and grew in a very unusual way by forming facetted enclosures around the primary precipitates. (orig.)

  10. Magnetic structures of Er6Mn23 and Dy6Mn23

    International Nuclear Information System (INIS)

    Ouladdiaf, B.; Deportes, J.; Rodriguez-Carvajal, J.

    1995-01-01

    The R 6 Mn 23 (R=rare earth) compounds crystallize in the cubic Th 6 Mn 23 -type structure with space group Fm3m. Powder neutron-diffraction experiments were performed on Dy 6 Mn 23 and Er 6 Mn 23 . The magnetic unit cell coincides with the chemical one. The R moments have a ferromagnetic non-collinear arrangement, whereas the Mn moments are parallel to the [1 1 1] direction. The magnetic structures belong to the three-dimensional Γ 5g irreducible representation of Fm3m associated with the wave vector K=[0 0 0]. The spin configurations in both compounds result from the competition between the R-R, R-Mn magnetic interactions and the crystal electric field on the R ions. (orig.)

  11. Millimeter-wave spectroscopy of CrC (X(3)Σ(-)) and CrCCH (X̃ (6)Σ(+)): Examining the chromium-carbon bond.

    Science.gov (United States)

    Min, J; Ziurys, L M

    2016-05-14

    Pure rotational spectroscopy of the CrC (X(3)Σ(-)) and CrCCH (X̃ (6)Σ(+)) radicals has been conducted using millimeter/sub-millimeter direct absorption methods in the frequency range 225-585 GHz. These species were created in an AC discharge of Cr(CO)6 and either methane or acetylene, diluted in argon. Spectra of the CrCCD were also recorded for the first time using deuterated acetylene as the carbon precursor. Seven rotational transitions of CrC were measured, each consisting of three widely spaced, fine structure components, arising from spin-spin and spin-rotation interactions. Eleven rotational transitions were recorded for CrCCH and five for CrCCD; each transition in these cases was composed of a distinct fine structure sextet. These measurements confirm the respective (3)Σ(-) and (6)Σ(+) ground electronic states of these radicals, as indicated from optical studies. The data were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation constants have been accurately determined for all three species. The spectroscopic parameters for CrC were significantly revised from previous optical work, while those for CrCCH are in excellent agreement; completely new constants were established for CrCCD. The chromium-carbon bond length for CrC was calculated to be 1.631 Å, while that in CrCCH was found to be rCr-C = 1.993 Å - significantly longer. This result suggests that a single Cr-C bond is present in CrCCH, preserving the acetylenic structure of the ligand, while a triple bond exists in CrC. Analysis of the spin constants suggests that CrC has a nearby excited (1)Σ(+) state lying ∼16 900 cm(-1) higher in energy, and CrCCH has a (6)Π excited state with E ∼ 4800 cm(-1).

  12. Effect of the composition on the structure of Cr-Al-C investigated by combinatorial thin film synthesis and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, R.; Sun, Z.; Music, D.; Schneider, J.M. [Materials Chemistry, RWTH-Aachen, Kopernikusstr. 16, D-52074 Aachen (Germany)

    2004-11-01

    The effect of the chemical composition on the structure of Cr-Al-C was studied by combinatorial thin film synthesis. By changing the Cr/C ratio from 1.72 to 3.48 and the Cr/Al ratio from 1.42 to 4.18 the formation of Cr{sub 2}AlC, Cr{sub 2}Al and Cr{sub 23}C{sub 6} phases was observed. Furthermore, based on X-ray diffraction a single phase Cr{sub 2}AlC composition region is identified in the Cr-Al-C phase diagram. Throughout the studied composition range the lattice parameters of Cr{sub 2}AlC were independent of the chemical composition. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  13. A study on martensitic structure in Fe-4Cr-0.4C steel

    International Nuclear Information System (INIS)

    Won, S.B.

    1980-01-01

    Morphology, dependence of prior austenite grain size and packet size upon austenitizing temperature, distribution of lath width, and habit plane of martensitic structure in Fe-4Cr-0.4C steel has been studied by optical microscopy and transmission electron microscopy. The results obtained are as follows. 1) Optical microstructures of martensitic Fe-4Cr-0.4C steel consist of lath martensite and lens martensite. Also the four types of morphology are observed by electron microscopy. The most common morphologies are a regular paralleled martensite and an irregular dovetailed lath martensite, while the remainder of microstructures consists mainly of groups of internally twinned martensite and autotempered laths. 2) Prior austenite grain size and packet size increased with austenizing temperature, and also the numbers of lath contained in a prior austenite grain or a packet are increased with austenizing temperature. 3) The mean width of lath in Fe-4Cr-0.4C steel is about 0.23μm and most of lath widths are below 0.5μm. 4) Martensite habit plane of Fe-4Cr-0.4C steel is nearly [110]α'. (author)

  14. Coarsening of (Fe, Cr)23C6 carbide phase on the tempering of 14Kh17N2 chromium-nickel steel

    International Nuclear Information System (INIS)

    Psarev, V.I.

    2002-01-01

    Paper lists the results of computer analysis of distribution according to sizes (Fe, Cr) 23 C 6 microparticles resulting from 14Kh17N2 steel tempering under 700 Deg C. Data were obtained at the maximum beneficial magnification of a light microscope. The mentioned curves of distribution densities are characterized by more reliable run from most permissible sizes of dispersed particles. Application of general rules of distributions and of previously elaborated procedure to identify experimental histograms with theoretical distributions enables to derive valuable information on dynamics of coarsening of a disperse phase in this case, as well [ru

  15. Thermo-mechanical treatment of low-cost alloy Ti-4.5Al-6.9Cr-2.3Mn and microstructure and mechanical characteristics

    Science.gov (United States)

    Chen, Guangyao; Kang, Juyun; Wang, Shusen; Wang, Shihua; Lu, Xionggang; Li, Chonghe

    2018-04-01

    In this study, the thermo-mechanical treatment process for low-cost Ti-4.5Al-6.9Cr-2.3Mn alloy were designed on the basis of assessment of Ti-Al-Cr-Mn thermodynamic system. The microstructure and mechanical properties of Ti-4.5Al-6.9Cr-2.3Mn forging and sheet were investigated by using the OM, SEM and universal tensile testing machine. The results show that both the forging and sheet were consisted of α + β phase, which is consistent with the expectation, and no element Cr and Mn existed in the grain boundaries of the sheet after quenching, and the C14 laves phase was not detected. The average ultimate tensile strength (σ b), 0.2% proof strength (σ 0.2) and elongation (EI) of alloy sheet after quenching can reach 1059 MPa, 1051 MPa and 24.6 Pct., respectively. Moreover, the average ultimate tensile strength of Ti-4.5Al-6.9Cr-2.3Mn forgings can reach 1599 MPa and the average elongation can reach 11.2 Pct., and a more excellent property of Ti-4.5Al-6.9Cr-2.3Mn forging is achieved than that of TC4 forging. It provides a theoretical support for further developing this low-cost alloy.

  16. Magnetic structures of Er{sub 6}Mn{sub 23} and Dy{sub 6}Mn{sub 23}

    Energy Technology Data Exchange (ETDEWEB)

    Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France); Deportes, J. [Laboratoire de Magnetisme L. Neel, C.N.R.S., BP 166, 38042 Grenoble Cedex 9 (France); Rodriguez-Carvajal, J. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)]|[Laboratoire Leon Brillouin (CEA-CNRS), Centre d`Etudes de Saclay, Gif sur Yvette (France)

    1995-08-01

    The R{sub 6}Mn{sub 23} (R=rare earth) compounds crystallize in the cubic Th{sub 6}Mn{sub 23}-type structure with space group Fm3m. Powder neutron-diffraction experiments were performed on Dy{sub 6}Mn{sub 23} and Er{sub 6}Mn{sub 23}. The magnetic unit cell coincides with the chemical one. The R moments have a ferromagnetic non-collinear arrangement, whereas the Mn moments are parallel to the [1 1 1] direction. The magnetic structures belong to the three-dimensional {Gamma}{sub 5g} irreducible representation of Fm3m associated with the wave vector K=[0 0 0]. The spin configurations in both compounds result from the competition between the R-R, R-Mn magnetic interactions and the crystal electric field on the R ions. (orig.).

  17. Study of the M23C6 precipitation in AISI 304 stainless steel by small angle neutron scattering

    International Nuclear Information System (INIS)

    Boeuf, A.; Caciuffo, R.G.M.; Institut Max von Laue - Paul Langevin, 38 - Grenoble; Ancona Univ.; Melone, S.; Puliti, P.; Rustichelli, F.; Institut Max von Laue - Paul Langevin, 38 - Grenoble; Ancona Univ.; Coppola, R.

    1985-01-01

    The results of some small-angle neutron scattering (SANS) experiments on M 23 C 6 (M=Fe, Cr) carbide precipitation in AISI 304 stainless steel, aged at different temperatures during different times, are presented. The total volume fraction, the total surface of precipitates per unit sample volume and the size distribution functions of the M 23 C 6 carbides were determined. (orig.)

  18. P-type Al-doped Cr-deficient CrN thin films for thermoelectrics

    Science.gov (United States)

    le Febvrier, Arnaud; Van Nong, Ngo; Abadias, Gregory; Eklund, Per

    2018-05-01

    Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over-stoichiometry in nitrogen (CrN1+δ) rock-salt structure is obtained. A p-type conduction is observed with nitrogen-rich CrN combined with aluminum doping. The Cr0.96Al0.04N1.17 film exhibited a high Seebeck coefficient and a sufficient power factor at 300 °C. These results are a starting point for designing p-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale.

  19. Structure change in 25 Cr - 20 Ni steels as a function of their Cr, Ni, Si and W content

    International Nuclear Information System (INIS)

    Gribaudo, L.M.; Durand, F.; Durand-Charre, M.

    1983-01-01

    The influence of varying the Cr, Ni, Si and W concentrations on the type and composition of the carbides of solidification and on the phase shift temperature is studied with 18 alloys of composition close to stainless steel-25-20 (AISI 310) composition. Experimental techniques used are differential thermal analysis, microprobe and scanning electron microscope. Crystallization is interpreted with the equilibrium diagram Ni-Cr-C. The formation of the interdendritic σ phase for a chromium rich alloys is interpreted with the phase equilibrium diagram of Fe-Ni-Cr-C. Mechanical properties and corrosion resistance are dependent on the morphology of the carbides M 7 C 3 and M 23 C 6 [fr

  20. Structural stability, electronic, mechanical and superconducting properties of CrC and MoC

    Energy Technology Data Exchange (ETDEWEB)

    Kavitha, M.; Sudha Priyanga, G. [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Iyakutti, K. [Department of Physics and Nanotechnology, SRM University, Chennai 603203, Tamilnadu (India)

    2016-02-01

    The structural, electronic, mechanical and superconducting properties of chromium carbide (CrC) and molybdenum carbide (MoC) are investigated using first principles calculations based on density functional theory (DFT). The computed ground state properties like equilibrium lattice constants and cell volume are in good agreement with available theoretical and experimental data. A pressure induced structural phase transition from tungsten carbide phase (WC) to zinc blende phase (ZB) and then zinc blende phase (ZB) to nickel arsenide phase (NiAs) are observed in both chromium and molybdenum carbides. Electronic structure reveals that these carbides are metallic at ambient condition. All the calculated elastic constants obey the Born–Huang stability criteria, suggesting that they are mechanically stable at normal and high pressure. The super conducting transition temperatures for CrC and MoC in WC phase are found to be 31.12 K and 17.14 K respectively at normal pressure. - Highlights: • Electronic and mechanical properties of CrC and MoC are investigated. • Pressure induced structural phase transition is predicted at high pressure. • Electronic structure reveals that these materials exhibit metallic behaviour. • Debye temperature values are computed for CrC and MoC. • Superconducting transition temperature values are computed.

  1. High temperature aging structures of Ni-20Cr-20W alloys

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1977-01-01

    High temperature aging structures and age hardening of Ni-20Cr-20W alloys developed as the superalloys for the nuclear energy steelmaking, and effects of C and Zr additions to the alloys and the effect of preheat treatment on these properties were studied. M 6 C, α-W and two kinds of M 23 C 6 having different lattice parameters were found as precipitates in the alloys. M 23 C 6 whose lattice parameter was around 10.7A precipitated in the early stage of aging at 700 0 C-1,150 0 C, and the carbide changed to M 6 C at higher temperature than 1,000 0 C, but it remained as a stable carbide at lower temperature than 900 0 C. α-W precipitated at 800 0 C-1,100 0 C after precipitation of M 23 C 6 and it disappeared with increase of M 6 C. M 23 C 6 having the larger lattice parameter (10.9A) precipitated transitionally in aging stage of 26 x 10 3 in Larson Miller parameter at 900 0 C and 1,000 0 C. Age hardening corresponded to the precipitation of M 23 C 6 and it was reduced by the double pre-heat-treatment. Zr addition and amount of C influenced on the aging structure and age hardening. Zr seemed to be a favorable element to stabilize the carbide. (auth.)

  2. First-principles study of structural phase transition, electronic, elastic and thermodynamic properties of C15-type Laves phase TiCr2 under pressure

    Science.gov (United States)

    He, Li-Zhi; Zhu, Jun; Zhang, Lin

    2018-02-01

    Phase transition of TiCr2 in C15 (MgCu2), C36 (MgNi2), C14 (MgZn2) structures have been studied by using the projector augmented wave method. It is found that C15-type is the most stable structure, which agrees with the results of Chen et al. At 0 K, the phase boundary of C15 to C36 is 207.79 GPa, and the phase transition from C36 to C14 is 265.61 GPa. Both the transition pressures decrease with increasing temperature. Phonon dispersion and elastic constants are calculated and found that C15-type TiCr2 is mechanically stable according to the elastic stability criteria and phonon dispersion analysis. Moreover, the pressure and temperature dependence of the specific heat, Debye temperature and thermal expansion coefficient are discussed, among them our calculated Debye temperature is consistent with the report of A. sari et al., however, it is far from the results of B. Mayer et al. and Chen et al.

  3. Phase stability, crystal structure and magnetism in (U1-xNbx)2 Ni21B6 and (UyNb1-y)3Ni20B6

    Science.gov (United States)

    Provino, Alessia; Bhattacharya, Amitava; Dhar, Sudesh K.; Pani, Marcella; Gatti, Flavio; Paudyal, Durga; Manfrinetti, Pietro

    Ternary phases with composition T2M21X6 and T3M20X6 (T = transition metal; M = 3 d metal; X = B, C, P) are reported to crystallize with the W2Cr21C6-type and Mg3Ni20B6-type, respectively (ternary ordered derivatives of the cubic Cr23C6-type, cF116). They attract interest due to their refractory, mechanical, and peculiar magnetic properties. Literature data on these compounds only concern apparently stoichiometric 2:21:6 and 3:20:6 phases. Often only nominal composition has been reported, with few structural refinements and no measurements of physical properties. Lack of detailed stoichiometry and crystallographic data does not allow sufficient understanding of the crystal chemistry and properties of these compounds. We studied stability, crystal structure and magnetism of (U1-xNbx)2 Ni21B6 and (UyNb1-y)3Ni20B6; stable phases are U2Ni21B6 and Nb3Ni20B6, as also confirmed by theoretical calculations. The two pristine compounds solubilize Nb and U, respectively, up to a given extent. The substitution of U by Nb leads to a structural change from the W2Cr21C6- to the Mg3Ni20B6-type. While U2Ni21B6 is a Pauli paramagnet (itinerant non-magnetic state of U-5 f electrons), in agreement with literature, magnetization data for (UyNb1-y)3 Ni20B6 show itinerant ferromagnetism with TC >300 K.

  4. Electronic structure and mechanical properties of Cr7C3

    International Nuclear Information System (INIS)

    Music, D.; Kreissig, U.; Mertens, R.; Schneider, J.M.

    2004-01-01

    We have studied the Cr 7 C 3 phase by means of ab initio calculations and found covalent-ionic Cr-C-Cr chains in a metallic matrix. Furthermore, the structure of thin films, synthesized by RF magnetron sputtering, is shown to be in good agreement with our theoretical prediction

  5. Microstructure of Fe-Cr-C hardfacing alloys with additions of Nb, Ti and, B

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.

    1987-01-01

    The abrasive wear of machine parts and tools used in the mining, earth moving, and transporting of mineral materials can be lowered by filler wire welding of hardfacing alloys. In this paper, the microstructures of Fe-Cr-C and Fe-Cr-C-Nb/Ti hardfacing alloys and deposits and those of newly developed Fe-Cr-C-B and Fe-Ti-Cr-C-B ones are described. They show up to 85 vol.% of primarily solidified coarse hard phases; i.e., Carbides of MC-, M/sub 7/C/sub 3/-, M/sub 3/C-type and Borides of MB/sub 2/-, M/sub 3/B/sub 2/-, M/sub 2/B-, M/sub 3/B-, M/sub 23/B/sub 6/-type, which are embedded in a hard eutectic. This itself consists of eutectic hard phases and a martensitic or austenitic metal matrix. The newly developed Fe-Cr-C-B alloys reach hardness values of up to 1200 HV and are harder than all purchased ones. The primary solidification of the MB/sub 2/-type phase of titanium requires such high amounts of titanium and boron that these alloys are not practical for manufacture as commercial filler wires

  6. Synthesis and structure determination of new open-framework chromium carboxylate MIL-105 or CrIII(OH).{O2C-C6(CH3)4-CO2}.nH2O

    International Nuclear Information System (INIS)

    Serre, Christian; Millange, Franck; Devic, Thomas; Audebrand, Nathalie; Van Beek, Wouter

    2006-01-01

    Two new three-dimensional chromium(III) dicarboxylate, MIL-105 or Cr III (OH).{O 2 C-C 6 (CH 3 ) 4 -CO 2 }.nH 2 O, have been obtained under hydrothermal conditions, and their structures solved using X-ray powder diffraction data. Both solids are structural analogs of the known Cr benzenedicarboxylate compound (MIL-53). Both contain trans corner-sharing CrO 4 (OH) 2 octahedral chains connected by tetramethylterephthalate di-anions. Each chain is linked by the ligands to four other chains to form a three-dimensional framework with an array of 1D pores channels. The pores of the high temperature form of the solid, MIL-105ht, are empty. However, MIL-105ht re-hydrates at room temperature to finally give MIL-105lt with pores channels filled with free water molecules (lt: low temperature form; ht: high temperature form). The thermal behaviour of the two solids has been investigated using TGA. Crystal data for MIL-105ht: monoclinic space group C2/c with a = 19.653(1) A, b = 9.984(1) A, c = 6.970(1) A, β = 110.67(1) o and Z = 4. Crystal data for MIL-105lt: orthorhombic space group Pnam with a = 17.892(1) A, b = 11.165(1) A, c = 6.916(1) A and Z = 4

  7. Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe2O6

    International Nuclear Information System (INIS)

    Batuk, Dmitry; De Dobbelaere, Christopher; Tsirlin, Alexander A.; Abakumov, Artem M.; Hardy, An; Van Bael, Marlies K.; Greenblatt, Martha; Hadermann, Joke

    2013-01-01

    Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe 2 O 6 is possible by the solution–gel method. • The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr 3+ for Mn 3+ substitution in the BiMnFe 2 O 6 structure. The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe 2 O 6 structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R I = 0.036, R P = 0.011) with only a slight decrease in the cell parameters associated with the Cr 3+ for Mn 3+ substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr x Mn 1−x Fe 2 O 6 (x = 0.2; 0.3) and parent BiMnFe 2 O 6 . Only T N slightly decreases upon Cr doping that indicates a very subtle influence of Cr 3+ cations on the magnetic properties at the available substitution rates

  8. The Observation of the Structure of M23C6/ γ Coherent Interface in the 100Mn13 High Carbon High Manganese Steel

    Science.gov (United States)

    Xu, Zhenfeng; Ding, Zhimin; Liang, Bo

    2018-03-01

    The M23C6 carbides precipitate along the austenite grain boundary in the 100Mn13 high carbon high manganese steel after 1323 K (1050 °C) solution treatment and subsequent 748 K (475 °C) aging treatment. The grain boundary M23C6 carbides not only spread along the grain boundary and into the incoherent austenite grain, but also grow slowly into the coherent austenite grain. On the basis of the research with optical microscope, a further investigation for the M23C6/ γ coherent interface was carried out by transmission electron microscope (TEM). The results show that the grain boundary M23C6 carbides have orientation relationships with only one of the adjacent austenite grains in the same planes: (\\bar{1}1\\bar{1})_{{{M}_{ 2 3} {C}_{ 6} }} //(\\bar{1}1\\bar{1})_{γ } , (\\bar{1}11)_{{{M}_{ 2 3} {C}_{ 6} }} //(\\bar{1}11)_{γ } ,[ 1 10]_{{{M}_{ 2 3} {C}_{ 6} }} //[ 1 10]_{γ } . The flat M23C6/ γ coherent interface lies on the low indexed crystal planes {111}. Moreover, in M23C6/ γ coherent interface, there are embossments which stretch into the coherent austenite grain γ. Dislocations distribute in the embossments and coherent interface frontier. According to the experimental observation, the paper suggests that the embossments can promote the M23C6/ γ coherent interface move. Besides, the present work has analyzed chemical composition of experimental material and the crystal structures of austenite and M23C6, which indicates that the transformation can be completed through a little diffusion for C atoms and a simple variant for austenite unit cell.

  9. Precipitation sequences in austenitic Fe-22Cr-21Ni-6Mo-(N) stainless steels

    International Nuclear Information System (INIS)

    Kim, S.-J.; Lee, T.-H.

    1999-01-01

    Precipitation sequence of nitrogen containing Fe-22Cr-21Ni-6Mo-N austenitic stainless steel has been investigated after aging at high temperatures, and compared with nitrogen free steel. The σ phases and M 23 C 6 carbides were observed along the grain boundaries as well as in the matrix in both of the solution treated specimens. The M 6 C carbides and chi phase appeared successively in between 3 hours and 24 hours depending on the nitrogen content. Main difference in aging behavior was the precipitation of fine nitrides. Aging for 24 hours and 168 hours of nitrogen containing steel resulted in the formation of fine Cr 2 N and faceted AlN nitrides. The crystallography, structure and morphology were analyzed with analytical electron microscopy. (orig.)

  10. Study of the structural and thermal stability of Li0.3Co2/3Ni1/6Mn1/6O2

    International Nuclear Information System (INIS)

    Mahmoud, Abdelfattah; Saadoune, Ismael; Difi, Siham; Sougrati, Moulay Tahar; Lippens, Pierre-Emmanuel; Amarilla, José Manuel

    2014-01-01

    Thermal and structural stabilities of the delithiated positive electrode material Li x Co 2/3 Ni 1/6 Mn 1/6 O 2 were studied by X-ray diffraction, magnetic and thermogravimetric analysis. In the opposite to the classical electrode materials LiNiO 2 and LiCoO 2 , the structural symmetry (S.G. R-3 m) of the starting material LiCo 2/3 Ni 1/6 Mn 1/6 O 2 is preserved during the electrochemical cycling with a small variation of the unit cell parameters. Squid measurements evidenced that practically no Ni 2+ ions were present in the lithium slab even after the lithium extraction process. For the thermal stability, the highly oxidized phase Li 0.3 Co 2/3 Ni 1/6 Mn 1/6 O 2 was tested. This delithiated phase undergoes only 5.16% weight loss after heating up to 600 °C. This weight loss has no effect on the structure symmetry as the starting α-NaFeO 2 type structure was preserved during the thermal treatment. The obtained results coupled to the excellent electrochemical features of LiCo 2/3 Ni 1/6 Mn 1/6 O 2 clearly showits ability to compete with the commercialized cathode materials

  11. Fracture of coherent interfaces between an fcc metal matrix and the Cr23C6 carbide precipitate from first principles

    Science.gov (United States)

    Barbé, Elric; Fu, Chu-Chun; Sauzay, Maxime

    2018-02-01

    It is known that microcrack initiation in metallic alloys containing second-phase particles may be caused by either an interfacial or an intraprecipitate fracture. So far, the dependence of these features on properties of the precipitate and the interface is not clearly known. The present study aims to determine the key properties of carbide-metal interfaces controlling the energy and critical stress of fracture, based on density functional theory (DFT) calculations. We address coherent interfaces between a fcc iron or nickel matrix and a frequently observed carbide, the M23C6 , for which a simplified chemical composition Cr23C6 is assumed. The interfacial properties such as the formation and Griffith energies, and the effective Young's modulus are analyzed as functions of the magnetic state of the metal lattice, including the paramagnetic phase of iron. Interestingly, a simpler antiferromagnetic phase is found to exhibit similar interfacial mechanical behavior to the paramagnetic phase. A linear dependence is determined between the surface (and interface) energy and the variation of the number of chemical bonds weighted by the respective bond strength, which can be used to predict the relative formation energy for the surface and interface with various chemical terminations. Finally, the critical stresses of both intraprecipitate and interfacial fractures due to a tensile loading are estimated via the universal binding energy relation (UBER) model, parametrized on the DFT data. The validity of this model is verified in the case of intraprecipitate fracture, against results from DFT tensile test simulations. In agreement with experimental evidences, we predict a much stronger tendency for an interfacial fracture for this carbide. In addition, the calculated interfacial critical stresses are fully compatible with available experimental data in steels, where the interfacial carbide-matrix fracture is only observed at incoherent interfaces.

  12. Crystal structure of 1,3-bis(2,3-dimethylquinoxalin-6-ylbenzene

    Directory of Open Access Journals (Sweden)

    Charles E. Diesendruck

    2015-12-01

    Full Text Available The title compound, C26H22N4 (I, was synthesized by C—H iridium-catalyzed borylation followed by Suzuki coupling. The molecular structure of (I consists of a central benzene ring with 3-dimethylquinoxalin-6-yl groups at the 1 and 3 positions. These 2,3-dimethylquinoxalin-6-yl groups twist significantly out of the plane of the benzene ring. There are intermolecular π–π interactions which result in a two-dimensional extended structure. The layers extend parallel to the ab plane and stack along the c axis.

  13. The origin of anisotropy and high density of states in the electronic structure of Cr2GeC by means of polarized soft x-ray spectroscopy and ab initio calculations

    OpenAIRE

    Magnuson, Martin; Mattesini, Maurizio; Bugnet, Matthieu; Eklund, Per

    2015-01-01

    The anisotropy in the electronic structure of the inherently nanolaminated ternary phase Cr$_{2}$GeC is investigated by bulk-sensitive and element selective soft x-ray absorption/emission spectroscopy. The angle-resolved absorption/emission measurements reveal differences between the in-plane and out-of-plane bonding at the (0001) interfaces of Cr$_{2}$GeC. The Cr $L_{2,3}$, C $K$, and Ge $M_{1}$, $M_{2,3}$ emission spectra are interpreted with first-principles density-functional theory (DFT)...

  14. Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe{sub 2}O{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Batuk, Dmitry, E-mail: Dmitry.batuk@ua.ac.be [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Tsirlin, Alexander A. [National Institute of Chemical Physics and Biophysics, 12618, Tallinn (Estonia); Abakumov, Artem M. [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); Hardy, An; Van Bael, Marlies K. [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Greenblatt, Martha [Department of Chemistry and Chemical Biology, Rutgers, State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey, 08854-8087 (United States); Hadermann, Joke [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium)

    2013-09-01

    Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe{sub 2}O{sub 6} is possible by the solution–gel method. • The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr{sup 3+} for Mn{sup 3+} substitution in the BiMnFe{sub 2}O{sub 6} structure. The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe{sub 2}O{sub 6} structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R{sub I} = 0.036, R{sub P} = 0.011) with only a slight decrease in the cell parameters associated with the Cr{sup 3+} for Mn{sup 3+} substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} (x = 0.2; 0.3) and parent BiMnFe{sub 2}O{sub 6}. Only T{sub N} slightly decreases upon Cr doping that indicates a very subtle influence of Cr{sup 3+} cations on the magnetic properties at the available substitution rates.

  15. Kinetics of M23C6 carbide growth in Type 316 stainless steel

    International Nuclear Information System (INIS)

    Skyrme, G.; Norbury, J.

    1980-11-01

    A mathematical model has been developed which describes the kinetics of the reduction in the dissolved carbon concentration in austenitic steels due to the precipitation of M 23 C 6 . It is assumed that carbon and chromium diffuse simultaneously and independently to carbide nucleation sites, and that at the carbide/matrix interface (a) the ratio of the fluxes of carbon and chromium is constant, and (b) the elements are in thermodynamic equilibrium. Two types of nucleation site have been considered, (a) at grain boundaries and (b) as isolated particles throughout the grains. Since the diffusion coefficient of carbon is several orders of magnitude greater than that of chromium, the carbon is shown to respond relatively rapidly to concentration changes and this fact has facilitated the formulation of approximate solutions to the equations. It is shown that the rate controlling process is the diffusion of chromium to the carbide site. The resultant equations are compared with available published data on carbide precipitation. Good agreement is found between the models and experimental observations. (U.K.)

  16. Microstructure and Mechanical Properties Evolution of the Al, C-Containing CoCrFeNiMn-Type High-Entropy Alloy during Cold Rolling.

    Science.gov (United States)

    Klimova, Margarita; Stepanov, Nikita; Shaysultanov, Dmitry; Chernichenko, Ruslan; Yurchenko, Nikita; Sanin, Vladimir; Zherebtsov, Sergey

    2017-12-29

    The effect of cold rolling on the microstructure and mechanical properties of an Al- and C-containing CoCrFeNiMn-type high-entropy alloy was reported. The alloy with a chemical composition (at %) of (20-23) Co, Cr, Fe, and Ni; 8.82 Mn; 3.37 Al; and 0.69 C was produced by self-propagating high-temperature synthesis with subsequent induction. In the initial as-cast condition the alloy had an face centered cubic single-phase coarse-grained structure. Microstructure evolution was mostly associated with either planar dislocation glide at relatively low deformation during rolling (up to 20%) or deformation twinning and shear banding at higher strain. After 80% reduction, a heavily deformed twinned/subgrained structure was observed. A comparison with the equiatomic CoCrFeNiMn alloy revealed higher dislocation density at all stages of cold rolling and later onset of deformation twinning that was attributed to a stacking fault energy increase in the program alloy; this assumption was confirmed by calculations. In the initial as-cast condition the alloy had low yield strength of 210 MPa with yet very high uniform elongation of 74%. After 80% rolling, yield strength approached 1310 MPa while uniform elongation decreased to 1.3%. Substructure strengthening was found to be dominated at low rolling reductions (<40%), while grain (twin) boundary strengthening prevailed at higher strains.

  17. Reheat cracking susceptibility of P23 (7CrWVMoNb9-6) steel welds made using matching and mis-matching filler metals

    Energy Technology Data Exchange (ETDEWEB)

    Nevasmaa, Pekka; Salonen, Jorma; Auerkari, Pertti; Rantala, Juhani; Holmstroem, Stefan [VTT Technical Research Centre of Finland, Espoo (Finland)

    2010-07-01

    Reheat cracking sensitivity of 7CrWVMoNb9-6 (P23) thick-section multipass welds has been investigated by Gleeble simulation, mechanical testing, fractography and metallography. The results demonstrate that the experimental weld metal made using a high-Nb-W-Ti-B type filler metal was sensitive to reheat cracking, with a reduction of area no more than 2-3% in the BWI reheat cracking (RC) test. Welds made using a high-W -low-Ti type filler metal with Nb content similar to the parent steel, as well as welds make using a Ni-Nb-Ti-free-(W-free) type filler metal with the chemical composition closer to P24 grade material, were more ductile and crack-resistant, though with reduced cross-weld creep strength. Fractography of RC test specimens showed evidence of pronounced localisation of damage at the prior austenite grain boundaries of the thermally reheated, experimental P23 weld metal. The reheat cracking susceptibility of the less ductile weld metal was apparently related both to the chemical composition (higher B, Nb and Ti content) and sub-structural features of the coarse-grained reheated weld metal microstructure. Appropriate single- and multi-cycle thermal Gleeble simulations to produce representative HAY and reheated weld metal microstructures (as function of peak temperature), in conjunction with the BWI RC test were successfully applied to characterise the reheat cracking sensitivity of the candidate weld metals and parent steel HAZ. (orig.)

  18. New ternary ordered structures in CuMPt6 (M=3d elements) alloys

    International Nuclear Information System (INIS)

    Das, Ananda Kumar; Nakamura, Reo; Takahashi, Miwako; Ohshima, Ken-ichi; Iwasaki, Hiroshi; Shishido, Toetsu

    2006-01-01

    X-ray and electron diffraction measurements were performed to investigate the structure and ordering behaviour of the ternary alloys CuMPt 6 (M=Ti, V, Cr, Mn, Fe, Co, and Ni). X-ray polycrystalline diffraction patterns of all the speciments quenched from 1000degC have shown that a single phase is formed at this stoichiometric composition. The alloys with M=Cr, Mn, Co, and Ni have the face-centred cubic (fcc) structure, while in the alloys with M=Ti, V, and Fe ordering has occurred and the structure is of the Cu 3 Au type. On annealing at lower temperatures ordering has been induced in the alloys with M=Cr, Mn, and Co and the structure is of the Cu 3 Au type, though the ordering in the last alloy has remained incomplete. Detailed X-ray diffraction measurements on single crystals of the CuMnPt 6 alloy have revealed that further ordering takes place and structure changes from the Cu 3 Au type into the cubic ABC 6 type with the unit cell as large 2 x 2 x 2 as the fcc unit cell, a new observation of the double-step ordering in the ternary fcc alloy. The corresponding transition temperatures are T c =970(±5)degC and T cl =750(±5)degC. (author)

  19. Microstructural Characteristics and m23c6 Precipitate Behavior of the Course-Grained Heat-Affected Zone of T23 Steel without Post-Weld Heat Treatment

    Directory of Open Access Journals (Sweden)

    Seong-Hyeong Lee

    2018-03-01

    Full Text Available The microstructural characteristics of a simulated heat-affected zone (HAZ in SA213-T23 (2.25Cr-1.6W steel used for boiler tubes employed in thermal power plants were investigated using nital, alkaline sodium picrate, and Murakami’s etchants. In order to investigate the microstructure formation process of the HAZ in the welding process, simulated HAZ specimens were fabricated at intervals of 100 °C for peak temperatures between 950 and 1350 °C, and the microstructural features and precipitate behavior at various peak temperatures were observed. The alkaline-sodium-picrate-etched microstructures exhibited a black dot or band, which was not observed in the natal-etched microstructure. As the temperature increased from 950 to 1350 °C, the black dot and band became wider and thicker. Experimental analyses using an electron probe micro-analyzer, electron backscatter diffraction, and transmission electron microscopy revealed the appearance of austenite in the black dot region at a peak temperature of 950 °C; its amount increased up to a peak temperature of 1050 °C and thereafter decreased as the peak temperature further increased. The amount of M23C6 decreased with an increase in peak temperature. Based on these results, we investigated the behaviors of austenite and M23C6 as functions of the peak temperature.

  20. Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

    International Nuclear Information System (INIS)

    Regus, Matthias; Mankovsky, Sergiy; Polesya, Svitlana; Kuhn, Gerhard; Ditto, Jeffrey; Schürmann, Ulrich; Jacquot, Alexandre; Bartholomé, Kilian; Näther, Christian; Winkler, Markus; König, Jan D.; Böttner, Harald; Kienle, Lorenz; Johnson, David C.; Ebert, Hubert; Bensch, Wolfgang

    2015-01-01

    The new metastable compound Cr 1+x Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni 2 In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr 1+x Sb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr 1+x Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr 1.6 Sb in Ni 2 In-type structure. • The new Cr-rich phase shows half-metallic behavior

  1. Bulk Kosterlitz-Thouless Type Molecular Superconductor β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6.

    Science.gov (United States)

    Martin, Lee; Lopez, Jordan R; Akutsu, Hiroki; Nakazawa, Yasuhiro; Imajo, Shusaku

    2017-11-20

    A new molecular superconductor, β″-(BEDT-TTF) 2 [(H 2 O)(NH 4 ) 2 Cr(C 2 O 4 ) 3 ]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C 2 O 4 ) 3 3- . The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH 4 + and Λ-Cr(C 2 O 4 ) 3 3- (layer B), layers of (H 2 O)(NH 4 )18-crown-6 (layer C), and layers of NH 4 + and Δ-Cr(C 2 O 4 ) 3 3- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement, this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β″). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to T zero at 1.8K, and the transition of α of V ∝ I α from 1 to 3 on I-V curves strongly suggest that the superconducting transition is very close to a Kosterlitz-Thouless transition. The magnetic field dependence of the superconducting critical temperature parallel to the conducting plane gives an upper critical field μ 0 H c2∥ > 8 T, which is over the calculated Pauli-Clogston limit for this material.

  2. Synthesis and structural stability of Cr-doped Li2MnSiO4/C cathode materials by solid-state method

    Science.gov (United States)

    Cheng, Hong-Mei; Zhao, Shi-Xi; Wu, Xia; Zhao, Jian-Wei; Wei, Lei; Nan, Ce-Wen

    2018-03-01

    The crystal structure of the Li2MnSiO4 cathode material would collapse during the charge and discharge process because of that the Mn-O coordination polyhedron changed from [MnO4] into [MnO6] in the process of Mn+2 to Mn+4, but the Cr element could remain [CrO4] crystal ligand from Cr+2 to Cr+4, so Cr element substitution was used to improve the structural stability of the Li2MnSiO4 cathode material. In this work, Li2Mn1-xCrxSiO4/C nanocomposites were synthesized by solid-state method. XRD, SEM and TEM observations show that the as-prepared Li2Mn1-xCrxSiO4/C materials presents an orthorhombic crystal structure (S.G. Pmn21), the particle size of Li2Mn1-xCrxSiO4/C powder ranges from 50 to 100 nm. The XRD and XPS results indicate that Cr+2 is successfully doped into Li2MnSiO4 lattice and has well compatibility with Li2MnSiO4. The electrochemical results display that Li2Mn92.5%Cr7.5%SiO4/C exhibits significantly enhanced cycle stability and discharge capability. The initial discharge capacity of the Li2Mn92.5%Cr7.5%SiO4/C sample is 255 mAh g-1, and the discharge capacity was still about 60 mAh g-1 after 50 cycles. Furthermore, the XRD patterns, TEM images and Raman analysis reveal that the Cr doping enhances the structural stability of Li2Mn1-xCrxSiO4/C and improves the electrochemical activity of the cathode. Thus, the Li2Mn92.5%Cr7.5%SiO4/C have shown potential applications for lithium ion batteries.

  3. Changes of structure and properties of cast steels GX10NiCrNb32-20 and GX10NiCrNb3-25 after long-term tempering at 600-1000 C

    International Nuclear Information System (INIS)

    Gommans, R.; Schrijen, H.; Sundermann, J.; Steinkusch, W.; Hering, W.

    2001-01-01

    Low-alloy cast steels of type GX 10NiCrNb 32.20 are commonly used for the outlet section of reformer and cracker tubes for the temperature range of 600-1000 C. There was a lack of data on the ductility of the 25%Cr alloyed cast steel GX10NiCrNb 35.25 at room temperature after tempering, which was investigated in a joint project of Pose-Marre and DSM. Mechanical tests were carried out at room temperature and at elevated temperatures. Apart from light microscopy, also SEM/EDX, SAM and TEM analyses were carried out. The 25% alloy has lower ductility than the 20% alloy, owing primarily to the more pronounced development of M 6 C carbide from primary NbC carbide, which takes up Ni and Si during tempering. The microstructure and composition of the M 6 C carbide wre not fully clarified. Information is presented on the potential application of low-carbon materials of the type GX10NiCrNb35.25 [de

  4. Investigation of Y6Mn23 and YMn12 intermetallic alloys under high hydrogen pressure

    Science.gov (United States)

    Filipek, S. M.; Sato, R.; Kuriyama, N.; Tanaka, H.; Takeichi, N.

    2010-03-01

    Among three intermetallic compounds existing in Y-Mn system the YMn2 and Y6Mn23 can easily form interstitial hydrides while for YMn12 existence of hydride has never been reported. At moderate hydrogen pressure YMn2 and Y6Mn23 transform into YMn2H4.5 and Y6Mn23H25 respectively. At high hydrogen pressure the YMn2 (C15 or C14 parent structure) forms a unique YMn2H6 (s.g. Fm3m) complex hydride of fluorite structure in which one Mn atom Mn(1) and Y randomly occupy the 8c sites while second manganese (Mn2) in position 4a forms complex anion with 6 hydrogen atoms located in positions 24e. Formation of YMn2H6 independently of the structure of parent phase (C14 or C15) as well as occupation of the same site (8c) by Y and Mn(1) atoms suggested that also Y6Mn23 and YMn12 could transform into YMn2H6 - type hydride in which suitable number of Y atoms will be substituted by Mn(1) in the 8c positions. This assumption was confirmed by exposing R6Mn23 and RMn12 to 1 GPa of hydrogen pressure at 1000C. Formation of (RxMn2-x)MnH6 (where x = 18/29 or 3/13 for R6Mn23 and RMn12 hydrides respectively) was confirmed by XRD. Hydrogen concentration in both R6Mn23 and RMn12 based hydrides reached H/Me = 2 thus value two times higher than in R6Mn23H25.

  5. Cr/B{sub 4}C multilayer mirrors: Study of interfaces and X-ray reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Burcklen, C.; Meltchakov, E.; Jérome, A.; Rossi, S. de; Delmotte, F. [Laboratoire Charles Fabry, Institut d' Optique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau Cedex (France); Soufli, R. [Laboratoire Charles Fabry, Institut d' Optique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau Cedex (France); Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Dennetiere, D.; Polack, F.; Capitanio, B.; Thomasset, M. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, BP 48F-91192 Gif sur Yvette Cedex (France); Gullikson, E. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720 (United States)

    2016-03-28

    We present an experimental study of the effect of layer interfaces on the x-ray reflectance in Cr/B{sub 4}C multilayer interference coatings with layer thicknesses ranging from 0.7 nm to 5.4 nm. The multilayers were deposited by magnetron sputtering and by ion beam sputtering. Grazing incidence x-ray reflectometry, soft x-ray reflectometry, and transmission electron microscopy reveal asymmetric multilayer structures with a larger B{sub 4}C-on-Cr interface, which we modeled with a 1–1.5 nm thick interfacial layer. Reflectance measurements in the vicinity of the Cr L{sub 2,3} absorption edge demonstrate fine structure that is not predicted by simulations using the currently tabulated refractive index (optical constants) values for Cr.

  6. On the sintering behaviour of steel bonded TiC-Cr3C2 and TiC-Cr3C2-WC mixed carbides

    International Nuclear Information System (INIS)

    Stojanov, L.G.; Exner, H.E.

    1978-01-01

    Powder mixtures of TiC+Cr 3 C 2 and TiC+Cr 3 C 2 + WC were hot pressed to nearly full density. The lattice parameter of the resulting cubic mixed crystal decreases linearly with increasing additions of Cr 3 C 2 and (Cr 3 C 2 +WC 1:1). Microhardness increases with Cr 3 C 2 content up to 20 wt.%. By addition of WC, microhardness is increased further and reaches a maximum value of approx. 38 000 MN/m 2 for 20 wt.% Cr 3 C 2 and 20 wt.% WC. From these solid solutions powder compositions of Ferro-TiC type were produced by milling with 55 wt.% Fe and 0.4 wt.% C. The sintering behaviour of these powders was studied in a vacuum dilatometer. The pronounced increase of shrinkage by Cr 3 C 2 and higher amounts of Cr 3 C 2 +WC dissolved in TiC previous to binder phase melting is attributed to the increased solubility of the carbide in solid iron. Presintering at 700 0 C in hydrogen has a negative influence on sintering activity and requires much higher temperatures for complete densification during subsequent vacuum sintering. (orig.) [de

  7. Thermal stability of nanocomposite CrC/a-C:H thin films

    International Nuclear Information System (INIS)

    Gassner, G.; Mayrhofer, P.H.; Patscheider, J.; Mitterer, C.

    2007-01-01

    The thermal stability of low-friction Me-C/a-C:H coatings is important for their potential applications in the tool and automotive industry. Recently we showed that CrC x /a-C:H coatings prepared by unbalanced magnetron sputtering of a Cr target in Ar + CH 4 glow discharges exhibit a nanocomposite structure where metastable fcc CrC nanocrystals are encapsulated by an a-C:H phase. Here, we present the structural evolution of these nanocomposite CrC/a-C:H coatings during annealing. High-temperature X-ray diffraction in vacuum and differential scanning calorimetry (DSC) combined with thermo-gravimetric analysis in Ar atmosphere indicate decomposition of the formed metastable fcc CrC phase and subsequent formation of Cr 3 C 2 and Cr 7 C 3 and structural transformation of the a-C:H matrix phase towards higher sp 2 bonding contents at temperatures above 450 deg. C. Combined DSC and mass spectrometer analysis as well as elemental profiling after annealing in vacuum by elastic recoil detection analysis relate this transformation to the loss of bonded hydrogen at temperatures above 200 deg. C. Due to these structural changes the coefficient of friction depends on the annealing temperature of the nanocomposite a-C:H coatings and shows a minimum of ∼ 0.13 for T = 200 deg. C. The more complex tribochemical reactions, influenced by the hydrogen loss from the coating during in-situ high temperatures ball-on disc tests, result in coefficient of friction values below 0.05 for T < 120 deg. C

  8. Et2NH2C6H3(CO23SnBr2.4H2O: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    DAOUDA NDOYE

    2014-01-01

    Full Text Available The title compound has been obtained on allowing [C6H3(CO23(Et2NH23] to react with SnBr4. The molecular structure of Et2NH2C6H3(CO23SnBr2.4H2O has been determined on the basis of the infrared data. The suggested structure is a dimer in which each tin atom is hexacoordinated by two chelating C6H3(CO233- anions and two Br atoms. Cy2NH2+cations are involved through hydrogen bonds with non-coordinating CO2 groups. The suggested structure is a cage.

  9. Investigation of Y6Mn23 and YMn12 intermetallic alloys under high hydrogen pressure

    International Nuclear Information System (INIS)

    Filipek, S M; Sato, R; Kuriyama, N; Tanaka, H; Takeichi, N

    2010-01-01

    Among three intermetallic compounds existing in Y-Mn system the YMn 2 and Y 6 Mn 23 can easily form interstitial hydrides while for YMn 12 existence of hydride has never been reported. At moderate hydrogen pressure YMn 2 and Y 6 Mn 23 transform into YMn 2 H 4.5 and Y 6 Mn 23 H 25 respectively. At high hydrogen pressure the YMn 2 (C15 or C14 parent structure) forms a unique YMn 2 H 6 (s.g. Fm3m) complex hydride of fluorite structure in which one Mn atom Mn(1) and Y randomly occupy the 8c sites while second manganese (Mn2) in position 4a forms complex anion with 6 hydrogen atoms located in positions 24e. Formation of YMn 2 H 6 independently of the structure of parent phase (C14 or C15) as well as occupation of the same site (8c) by Y and Mn(1) atoms suggested that also Y 6 Mn 23 and YMn 12 could transform into YMn 2 H 6 - type hydride in which suitable number of Y atoms will be substituted by Mn(1) in the 8c positions. This assumption was confirmed by exposing R 6 Mn 23 and RMn 12 to 1 GPa of hydrogen pressure at 100 0 C. Formation of (R x Mn 2-x )MnH 6 (where x = 18/29 or 3/13 for R 6 Mn 23 and RMn 12 hydrides respectively) was confirmed by XRD. Hydrogen concentration in both R 6 Mn 23 and RMn 12 based hydrides reached H/Me = 2 thus value two times higher than in R 6 Mn 23 H 25 .

  10. Isothermal sections at 500 deg C of the Dy-V-Al and Dy-Cr-Al systems in the aluminium rich regions

    International Nuclear Information System (INIS)

    Rykhal', R.M.; Zarechnyuk, O.S.; Mats'kiv, O.P.

    1979-01-01

    X-ray diffraction and microscopic analyses have been used to investigate the ternary system dysprosium-vanadium-aluminium in the aluminium rich region. In the system Dy-V-Al two ternary compounds have been found: DyV 2 Al 20 (cubic structure, CeCr 2 Al 20 type, a=14.54 A and approximately DyVAl 8 (hexagonal crystal system, structure unknown, a=10.86, c=17.71 A, c/a=1.631). In the system dysprosium-chromium-aluminium three ternary compounds have been found: DyCr 2 Al 20 (cubic structure, CeCr 2 Al 20 type, a=14.39), approximately equal to DyCrAl 8 ) hexagonal crystal system, structure type unkown a=10.75, c=17.60 A, c/a=1.637) and DyCr 4 Al 8 (tetragonal structure, CeMn 4 Al 8 type, a=8.87, c=5.04 A, c/a=0.568). Isothermal sections of the systems Dy-V-Al and Dy-Cr-Al have been plotted at 500 deg C

  11. Structure and physical properties of Cr_5B_3-type Ta_5Si_3 and Ta_5Ge_3

    International Nuclear Information System (INIS)

    Yuan, Fang; Forbes, Scott; Ramachandran, Krishna Kumar; Mozharivskyj, Yurij

    2015-01-01

    The Cr_5B_3-type Ta_5Si_3 phase was prepared by arc-melting, while the Cr_5B_3-type Ta_5Ge_3 one was synthesized through sintering at 1000 °C. X-ray single crystal diffraction was employed to elucidate their structure. According to the magnetization measurements, both Ta_5Si_3 and Ta_5Ge_3 are Pauli paramagnets, with Ta_5Ge_3 showing a Curie-Weiss-like paramagnetic behavior at low temperatures likely due to presence of paramagnetic impurity. Both Ta_5Si_3 and Ta_5Ge_3 display a very low electrical resistivity from 2 to 300 K. The resistivity is constant below 20 K, but displays a positive temperature coefficient above 20 K. Electronic structure calculations with the TB-LMTO-ASA method support the metallic character of the two phases and suggest that the bonding is optimized in both phases. - Highlights: • Synthesis of Cr_5B_3-type Ta_5Si_3 and Ta_5Ge_3 phases with high purity by arc-melting and sintering, respectively. • Magnetization data and electrical resistivity of the Cr_5B_3-type Ta_5Si_3 and Ta_5Ge_3 phases. • Crystal and electronic structure analysis for Ta_5Si_3 and Ta_5Ge_3 phase by X-ray diffraction and TB-LMTO-ASA calculations.

  12. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    International Nuclear Information System (INIS)

    Rojas Jara, David

    2011-01-01

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M 23 C 6 carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M 23 C 6 precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure evolution and creep

  13. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Jara, David

    2011-03-21

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6} carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure

  14. Matrix Transformation in Boron Containing High-Temperature Co-Re-Cr Alloys

    Science.gov (United States)

    Strunz, Pavel; Mukherji, Debashis; Beran, Přemysl; Gilles, Ralph; Karge, Lukas; Hofmann, Michael; Hoelzel, Markus; Rösler, Joachim; Farkas, Gergely

    2018-03-01

    An addition of boron largely increases the ductility in polycrystalline high-temperature Co-Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ɛ (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co-17Re-23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ɛ to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co-17Re-23Cr-1.2Ta-2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0-1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.

  15. Crystallochemical features of solid solutions based on Ga/sub 2/3/Cr/sub 2/S/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Titov, V.V.; Kesler, Ya.A.; Gordeev, I.V.; Stupnikov, V.A.

    1988-04-01

    Ga/sub 2/3/Cr/sub 2/S/sub 4/ shows a rare type of phase transition where increases in temperature and pressure produce the disordered modification. A source of disordering can be isomorphous substitution in the tetrahedral sublattice. The authors therefore made and examined solid solutions of Ga/sub (2/3-2x/3)/M/sub x/(Cr/sub 2/)S/sub 4/ type, where M = Fe, Co, Ni, Cu. Specimens containing Fe and show a quasi-continuous solid-solution series, where the Fe system obeys Vegard's rule. Specimens containing nickel show a narrow ordering range. The most interesting results have been obtained for specimens containing copper. Cu/sub x/Ga/sub 2/3(1-x)/Cr/sub 2/S/sub 4/ specimens show a transition from a structure ordered on the tetrahedral positions, symmetry F/anti/43m, to the normal-spinel structure, Fd3m.

  16. Study of 2D MXene Cr{sub 2}C material for hydrogen storage using density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, A. [Department of Physics and National Centre for Nanosciences & Nanotechnology, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai 400 098 (India); Dashora, Alpa, E-mail: dashoralpa@gmail.com [UM-DAE Centre for Excellence in Basic Sciences, Vidyanagari, Santacruz (E), Mumbai 400 098 (India); Patel, N. [Department of Physics and National Centre for Nanosciences & Nanotechnology, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai 400 098 (India); Dipartimento di Fisica, Università degli Studi di Trento, I-38123 Povo, Trento (Italy); Miotello, A. [Dipartimento di Fisica, Università degli Studi di Trento, I-38123 Povo, Trento (Italy); Press, M.; Kothari, D.C. [Department of Physics and National Centre for Nanosciences & Nanotechnology, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai 400 098 (India)

    2016-12-15

    Highlights: • First-principles studies showed that Cr{sub 2}C MXene can store 7.6 wt.% of H{sub 2}. • 6.4 wt.% H{sub 2} can be reversibly stored at ambient temperature. • Charge transfer between H and Cr is responsible for the reversible H{sub 2} adsorption. • H-atom on hollow site between three Cr atoms is the most stable site. - Abstract: Hydrogen storage capacity of 2D MXene Cr{sub 2}C has been studied using density functional theory. Possibility to adsorb H{sub 2} molecule on Cr{sub 2}C surface at various sites has been studied. Among the studied adsorption sites on Cr{sub 2}C surface, few sites were found suitable for chemisorption and physisorption of H{sub 2} molecules. Few of the studied sites are also found to be suitable for Kubas-type interaction, which is useful for reversible hydrogen storage at ambient conditions. Electronic structure calculations and charge transfer analysis have been done to understand the interactions of adsorbed hydrogen with the Cr{sub 2}C layer. It has been found that the total hydrogen storage capacity of Cr{sub 2}C is 7.6 wt.% in which 1.2 wt.% of H is due to the chemisorption, 3.2 wt.% is bonded with Kubas-interaction and remaining 3.2 wt.% is bonded through weak electrostatic interactions (with binding energy of 0.26 eV/H{sub 2} and charge transfer of 0.09 e{sup −} to H atom from Cr atom). Thus the reversible hydrogen storage capacity at ambient conditions (controlled by hydrogen bonded with energies ranging from 0.1 to 0.4 eV/H{sub 2}, in the present case through Kubas and weak electrostatic interactions) is 6.4 wt.% which is greater than the 2017 DoE recommended target value of 5.5 wt.%.

  17. Structure of Ni-rich Ni--Cr--B--Si coating alloys

    International Nuclear Information System (INIS)

    Knotek, O.; Lugscheider, E.; Reimann, H.

    1975-01-01

    The structures of quaternary, nickel-rich Ni--Cr--B--Si alloys were analyzed at a constant boron content of 10 at. percent and a temperature of 850 0 C. The composition range for silicide formation was determined. In these quaternary alloys, known binary nickel silicides, nickel and chromium borides, and the ternary silico-boride Ni 6 Si 2 B were confirmed. A new composition for the W 5 Si 3 -type phase in the Ni--B--Si system was proposed. (U.S.)

  18. Hexagonal perovskites with cationic vacancies. 3. Structure determination on compounds of type Ba/sub 2/Bsub(1/3)sup(III)vacantsub(2/3)Resup(VII)O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Wischert, W; Treiber, U [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-09-01

    Compounds of type Ba/sub 2/Bsub(1/3)sup(III)vacantsub(2/3)Resup(VII)O/sub 6/ with Bsup(III) = rare earth, Y, Sc. In belong to the group of hexagonal perovskite stacking polytypes. For Bsup(III) = Gd, Y structure determinations with powder data have been performed. The refined R' factors are 9.11% for Ba/sub 2/Gdsub(1/3)vacantsub(2/3)ReO/sub 6/ and 12.07% for Ba/sub 2/Ysub(1/3)vacantsub(2/3)ReO/sub 6/. The structure represents a rhombohedral 12 L type (space group R3m) with the sequence hhcchhcchhcc. The lattice contains groups of three octahedra connected by common faces which are linked together by a single octahedron via common vertices. In the block of three face-sharing octahedra the central octahedral lattice site is vacant and the two outer positions are occupied by the rhenium atoms. According to this distribution direct contact of occupied face-sharing octahedra is absent.

  19. The structure, magnetism, and electrical-transport properties of the Heusler alloys Co2Cr1-xFexAl (x=0.2-0.6)

    International Nuclear Information System (INIS)

    Zhang Ming; Wolf, Anne L.; Zhang, L.; Tegus, O.; Brueck, Ekkes; Wu Guangheng; Boer, Frank R. de

    2005-01-01

    We synthesize the polycrystalline Heusler compounds Co 2 Cr 1-x Fe x Al (x=0.2-0.6). The x-ray diffraction patterns show A2 structure rather than L2 1 structure. The magnetic moment and the Curie temperature increase with increasing x. The electrical resistivity characterizes the Co 2 Cr 1-x Fe x Al compounds to be not typical metals and the temperature dependence of the resistivity changes from metallic to semiconductinglike behavior with increasing Cr concentrations. We attribute the fact, which we observe for most of the compounds smaller magnetic moments than the theoretical values and the low magnetoresistance in these alloys, to the considerably high level of Co-(Cr, Fe)-type disorder

  20. P-type Al-doped Cr-deficient CrN thin films for thermoelectrics

    DEFF Research Database (Denmark)

    Febvrier, Arnaud le; Van Nong, Ngo; Abadias, Gregory

    2018-01-01

    Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over......-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale....

  1. Sigma phases in an 11%Cr ferritic/martensitic steel with the normalized and tempered condition

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yinzhong, E-mail: shenyz@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Zhou, Xiaoling; Shi, Tiantian; Huang, Xi [School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Shang, Zhongxia [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Liu, Wenwen; Ji, Bo; Xu, Zhiqiang [School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2016-12-15

    At the present time 9–12% Cr ferritic/martensitic (F/M) steels with target operating temperatures up to 650 °C and higher are being developed in order to further increase thermal efficiency so as to reduce coal consumption and air pollution. An 11% Cr F/M steel was prepared by reference to the nominal chemical composition of SAVE12 steel with an expected maximum use temperature of 650 °C. The precipitate phases of the 11% Cr F/M steel normalized at 1050 °C for 0.5 h and tempered at 780 °C for 1.5 h were investigated by transmission electron microscopy. Except for Cr-/Cr-Fe-Co-rich M{sub 23}C{sub 6}, Nb-/V-/Ta-Nb-/Nd-rich MX, Fe-rich M{sub 5}C{sub 2}, Co-rich M{sub 3}C and Fe-Co-rich M{sub 6}C phases previously identified in the steel, two types of sigma phases consisting of σ-FeCr and σ-FeCrW were found to be also present in the normalized and tempered steel. Identified σ-FeCr and σ-FeCrW phases have a simple tetragonal crystal structure with estimated lattice parameters a/c = 0.8713/0.4986 and 0.9119/0.5053 nm, respectively. The compositions in atomic pct of the observed sigma phases were determined to be approximately 50Fe-50Cr for the σ-FeCr, and 30Fe-55Cr-10W in addition to a small amount of Ta, Co and Mn for the σ-FeCrW. The sigma phases in the steel exhibit various blocky morphologies, and appear to have a smaller amount compared with the dominant phases Cr-rich M{sub 23}C{sub 6} and Nb-/V-/Ta-Nb-rich MX of the steel. The σ-FeCr phase in the steel was found to precipitate at δ-ferrite/martensite boundaries, suggesting that δ-ferrite may rapidly induce the formation of sigma phase at δ-ferrite/martensite boundaries in high Cr F/M steels containing δ-ferrite. The formation mechanism of sigma phases in the steel is also discussed in terms of the presence of δ-ferrite, M{sub 23}C{sub 6} precipitation, precipitation/dissolution of M{sub 2}X, and steel composition. - Highlights: •Precipitate phases in normalized and tempered 11%Cr F/M steel are

  2. Microstructure and microhardness characterization of Cr{sub 3}C{sub 2}-SiC coatings produced by the plasma transferred arc method

    Energy Technology Data Exchange (ETDEWEB)

    Islak, Serkan [Kastamonu Univ. (Turkey). Cide Rifat Ilgaz Vocational High School; Eski, Oezkan [Kastamonu Univ. (Turkey). Kastamonu Vocational High School; Buytoz, Soner [Firat Univ., Elazig (Turkey). Dept. of Metallurgy and Materials Engineering; Karagoez, Muzaffer [Bartin Univ. (Turkey). Dept. of Metallurgical and Materials Engineering; Stokes, Joseph [Dublin City Univ. (Ireland). School of Mechanical and Manufacturing Engineering

    2012-07-01

    The purpose of this work was to investigate the coatings made of Cr{sub 3}C{sub 2} and SiC powder manufactured on AISI 304 stainless steel applied by the plasma transferred arc (PTA) welding process. SiC content in the produced coated layer was varied between 0-100 wt. % and the effect of SiC concentration on the microstructure and hardness of the coating was measured experimentally. SEM analyses revealed that the composite coatings had a homogeneous, nonporous, and crack-free microstructure. Dendrites and interdendrite eutectics formed on the coating layer, subject to the temperature gradient and the solidification ratio. There was a significant increase in the hardness of coating layers with the effect of the {gamma}-(Fe,Ni), Cr{sub 7}C{sub 3}, Cr{sub 23}C{sub 6}, Fe{sub 5}C{sub 2}, Cr{sub 3}Si, CrSi{sub 2}, Fe{sub 0.64}Ni{sub 0.36}, CFe{sub 15.1}, C-(Fe,Cr)-Si phases formed in the microstructure. In comparison to the substrate, the microhardness of the coatings produced by PTA were 2.5-3.5 times harder. (orig.)

  3. First-principles investigations of disorder effects on electronic structure and magnetic properties in Sr2CrMoO6

    International Nuclear Information System (INIS)

    Li, Q F; Zhu, X F; Chen, L F

    2008-01-01

    The electronic structures and magnetic properties are reported for ordered and disordered Sr 2 CrMoO 6 presenting oxygen vacancies or/and antisite defects (ASs). We investigate the stability of an antiparallel (AP) magnetic moment on Cr antisites and the calculations show that these solutions are more stable relative to the parallel solution for AS defects with or without oxygen vacancies. Electronic band structure calculations indicate that the perfect Sr 2 CrMoO 6 is half-metallic, and the half-metallic character is preserved for Sr 2 CrMoO 6 containing only oxygen vacancies, while the half-metallic nature is destroyed when 25% ASs (50% ASs) with or without oxygen vacancies is present. For 25% ASs with two oxygen vacancies, the system possibly shows nonmetallic behavior. The experimentally observed reduction of the magnetic moment mainly arises from an antiferromagnetic coupling of Cr-O-Cr (Cr-Cr) bonds in a disordered sample

  4. Cr6+-containing phases in the system CaO-Al2O3-CrO42--H2O at 23 °C

    Science.gov (United States)

    Pöllmann, Herbert; Auer, Stephan

    2012-01-01

    Synthesis and investigation of lamellar calcium aluminium hydroxy salts was performed to study the incorporation of chromate ions in the interlayer of lamellar calcium aluminium hydroxy salts. Different AFm-phases (calcium aluminate hydrate with alumina, ferric oxide, mono-anion phase) containing chromate were synthesized. These AFm-phases belong to the group of layered double hydroxides (LDHs). 3CaO·Al2O3·CaCrO4·nH2O and C3A·1/2Ca(OH)2·1/2CaCrO4·12H2O were obtained as pure phases and their different distinct interlayer water contents and properties determined. Solid solution of chromate-containing phases and tetracalcium-aluminate-hydrate (TCAH) were studied. The uptake of chromate into TCAH from solutions was proven. Chromate contents in solution decrease to <0.2 mg/l.

  5. 4,6-Dibromo-N-{3-[(4,6-dibromo-2,3-dimethylphenylimino]butan-2-ylidene}-2,3-dimethylaniline

    Directory of Open Access Journals (Sweden)

    Lina Huang

    2013-10-01

    Full Text Available The title compound, C20H20Br4N2, is a product of the condensation reaction of 4,6-dibromo-2,3-dimethylaniline and butane-2,3-dione. The molecule has a center of symmetry at the mid-point of the central C—C bond. The dihedral angle between the benzene ring and the 1,4-diazabutadiene plane is 78.3 (2°. Niether hydrogen bonding nor aromatic stacking is observed in the crystal structure.

  6. TiC reinforced cast Cr steels

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, O.N.; Hawk, J.A.; Schrems, K.K.

    2006-06-01

    A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5–4.5Ti, and 1–1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

  7. TiC-reinforced cast Cr steels

    Science.gov (United States)

    Doğan, Ö. N.; Hawk, J. A.; Schrems, K. K.

    2006-06-01

    A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5-4.5Ti, and 1-1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

  8. Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

    Science.gov (United States)

    Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

    2017-06-01

    Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

  9. Symmetry breaking and electrical conductivity of La0.7Sr0.3Cr0.4Mn0.6O3-δ perovskite as SOFC anode material

    International Nuclear Information System (INIS)

    Reyes-Rojas, A.; Alvarado-Flores, J.; Esparza-Ponce, H.; Esneider-Alcala, M.; Espitia-Cabrera, I.; Torres-Moye, E.

    2011-01-01

    Research highlights: → Perovskite-type La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -NiO nucleation kinetics. Symmetry-breaking by introducing Ni 2+ cations at 1050 deg. C. Phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm. At low Ni concentration ρ resistivity decreases when increasing the temperature. For Ni concentration higher than 25% ρ resistivity increases. - Abstract: This work is focused on nanocrystalline solid oxide fuel cell synthesis and characterization (SOFC) anodes of La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ (perovskite-type) with Nickel. Perovskite-type oxide chemical reactivity, nucleation kinetics and phase composition related with La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -NiO to La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -Ni transformation have been analyzed. SOFC anode powders were obtained by sol-gel synthesis, using polyvinyl alcohol as an organic precursor to get a porous cermet electrode after sintering at 1365 deg. C and oxide reduction by hydrogen at 800 deg. C/1050 deg. C for 8 h in a horizontal tubular reactor furnace under 10% H 2 /N 2 atmosphere. Composite powders were compressed into 10-mm diameter discs with 25-75 wt% Ni. Electrical and structural characterization by four-point probe method for conductivity, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Rietveld method were carried out. Symmetry-breaking by phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm has been identified and confirmed by XRD and Rietveld method which can be produced by introducing Ni 2+ cations in the perovskite solid solution. Rietveld analysis suggests that Ni contents are directly proportional to La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 NiO 3.95 tetragonal structure cell volume and inversely proportional to Ni cubic structure cell volume after reduction at 1050 deg. C. Kinetic analysis indicated that the Johnson-Mehl-Avrami equation is able to provide a good fit to phase

  10. Investigation of Y{sub 6}Mn{sub 23} and YMn{sub 12} intermetallic alloys under high hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Filipek, S M; Sato, R [Inst. of Phys. Chem. PAS, ul. Kasprzaka 44, 01-224 Warsaw (Poland); Kuriyama, N; Tanaka, H; Takeichi, N, E-mail: smf@ichf.edu.p [National Institute of Adv. Ind. Science and Techn. 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2010-03-01

    Among three intermetallic compounds existing in Y-Mn system the YMn{sub 2} and Y{sub 6}Mn{sub 23} can easily form interstitial hydrides while for YMn{sub 12} existence of hydride has never been reported. At moderate hydrogen pressure YMn{sub 2} and Y{sub 6}Mn{sub 23} transform into YMn{sub 2}H{sub 4.5} and Y{sub 6}Mn{sub 23}H{sub 25} respectively. At high hydrogen pressure the YMn{sub 2} (C15 or C14 parent structure) forms a unique YMn{sub 2}H{sub 6} (s.g. Fm3m) complex hydride of fluorite structure in which one Mn atom Mn(1) and Y randomly occupy the 8c sites while second manganese (Mn2) in position 4a forms complex anion with 6 hydrogen atoms located in positions 24e. Formation of YMn{sub 2}H{sub 6} independently of the structure of parent phase (C14 or C15) as well as occupation of the same site (8c) by Y and Mn(1) atoms suggested that also Y{sub 6}Mn{sub 23} and YMn{sub 12} could transform into YMn{sub 2}H{sub 6} - type hydride in which suitable number of Y atoms will be substituted by Mn(1) in the 8c positions. This assumption was confirmed by exposing R{sub 6}Mn{sub 23} and RMn{sub 12} to 1 GPa of hydrogen pressure at 100{sup 0}C. Formation of (R{sub x}Mn{sub 2-x})MnH{sub 6} (where x = 18/29 or 3/13 for R{sub 6}Mn{sub 23} and RMn{sub 12} hydrides respectively) was confirmed by XRD. Hydrogen concentration in both R{sub 6}Mn{sub 23} and RMn{sub 12} based hydrides reached H/Me = 2 thus value two times higher than in R{sub 6}Mn{sub 23}H{sub 25}.

  11. TEM characterization of microstructure evolution of 12%Cr heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, D.; Prat, O.; Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

    2010-07-01

    A detailed characterization of the microstructure evolution of 12%Cr heat resistant steels at different creep times (100 MPa / 650 C / 8000 h) were carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. (orig.)

  12. Biferroic LuCrO3: Structural characterization, magnetic and dielectric properties

    International Nuclear Information System (INIS)

    Durán, A.; Meza F, C.; Morán, E.; Alario-Franco, M.A.; Ostos, C.

    2014-01-01

    Multiferroic LuCrO 3 perovskite-type structure (Pbnm) obtained via auto-ignition synthesis was characterized by a combination of X-ray diffraction (XRD) and thermogravimetric (TG) techniques, and through magnetization and permittivity measurements. Results showed that amorphous combustion powders were fully transformed to orthorhombic LuCrO 3 structure at 1200 K after the first LuCrO 4 crystallization at 700 K. The magnetic response displays thermal irreversibility between zero-field-cooling and field-cooling condition which is due to spin canted AF switching at 116 K. Accordingly, a hysteresis loop in the M(H) data confirms weak ferromagnetism in LuCrO 3 . On the other hand, the permittivity measurement shows a broad peak transition typical of relaxor-type ferroelectrics transition at ∼450 K. Electrical conductivity increases as temperature increases showing an anomaly around the diffuse phase transition. The diffuse phase transition and the formation of the charge carriers are discussed in terms of a local distortion around the Lu Site. - Highlights: • Multiferroic LuCrO 3 was successfully obtained via auto-ignition synthesis. • Amorphous powder is transformed first to LuCrO 4 (700 K) and next to LuCrO 3 (1100 K). • The CrO 6 octahedra are tilted away and rotates from the ideal octahedral shape. • LuCrO 3 exhibits a canted AFM transition (116 K) and a relaxor ferroelectric behavior. • Tilting and rotation of CrO 6 octahedra influenced transport properties on LuCrO 3

  13. Microstructure, mechanical and tribological properties of CrSiC coatings sliding against SiC and Al{sub 2}O{sub 3} balls in water

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhiwei [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics and Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Nanjing Forestry University, Nanjing 210037 (China); Zhou, Fei, E-mail: fzhou@nuaa.edu.cn [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics and Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing 210016 (China); Chen, Kangmin [Center of Analysis, Jiangsu University, Zhenjiang 212013 (China); Wang, Qianzhi [Department of Mechanical Engineering, Keio University, Yokohama 2238522 (Japan); Zhou, Zhifeng [Advanced Coatings Applied Research Laboratory, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China); Yan, Jiwang [Department of Mechanical Engineering, Keio University, Yokohama 2238522 (Japan); Li, Lawrence Kwok-Yan [Advanced Coatings Applied Research Laboratory, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China)

    2016-04-15

    Graphical abstract: CrSiC coatings were speculated to be X-ray amorphous (A). Although the hardness of coatings fluctuated slightly (13.2–13.8 GPa), the CrSiC coatings showed poor wear resistance due to the decline of the crack resistance and toughness. Moreover, the friction coefficient (0.24–0.31) and the wear rate (2.97–7.66 × 10{sup −6} mm{sup 3}/Nm) of CrSiC/SiC trobopairs were lower than those of CrSiC/Al{sub 2}O{sub 3} tribopairs (B and C). - Highlights: • CrSiC coatings with Si content of 2.0–7.4 at.% were deposited via adjusting the TMS flow. • The amorphous structure in the CrSiC coatings was presented. • No obvious fluctuations of hardness (about 13 GPa) were observed with TMS flow. • CrSiC/SiC tribopairs showed better tribological performance than CrSiC/Al{sub 2}O{sub 3} tribopairs. - Abstract: CrSiC coatings with different silicon contents were prepared using unbalanced magnetron sputtering via adjusting trimethylsilane (Si(CH{sub 3}){sub 3}H) flows. Their phase structure, bonding structure, microstructure and hardness were characterized by X-ray diffraction (XRD), X-ray photoelectrons spectroscopy (XPS), a field emission scanning electron microscope (FESEM) and nano-indenter, respectively. The tribological properties of CrSiC coatings sliding against SiC and Al{sub 2}O{sub 3} balls were investigated in water. The results showed that the CrSiC coatings were speculated to be X-ray amorphous. Although the hardness of coatings fluctuated slightly (13.2–13.8 GPa), the coatings showed poor wear resistance due to the decline of the crack resistance and toughness. Moreover, the friction coefficient (0.24–0.31) and the wear rate (2.97–7.66 × 10{sup −6} mm{sup 3}/Nm) of CrSiC/SiC trobopairs were lower than those of CrSiC/Al{sub 2}O{sub 3} tribopairs.

  14. Microstructural characterization of second phases in X10CrMoVNb9-1 and 12CrMoWCuVNb steels after long steam exposure time at 550 C

    International Nuclear Information System (INIS)

    Rodak, Kinga; Hernas, Adam; Vodarek, Vlastimil

    2015-01-01

    Microstructural changes in high alloy (9-12% Cr) creep resistant martensitic X10CrMoVNb9-1 and 12CrMoW . CuVNb steels after 100 000 h of steam exposure at 550 C have been studied using scanning transmission electron microscopy. Precipitates were identified using electron diffraction patterns and energy dispersive X-ray spectroscopy analysis. After long time exposure, a significant coarsening of M 23 C 6 carbides, and intensive precipitation of the coarse Laves phase were observed. Moreover, in the 12CrMoW . CuVNb steel, a low amount of the modified Z-phase particles was detected. The microstructures of the X10Cr . MoVNb9-1 and 12CrMoWCuVNb steels after 100 000 h of exposure differ in several aspects.

  15. Microstructural characterization of second phases in X10CrMoVNb9-1 and 12CrMoWCuVNb steels after long steam exposure time at 550 C

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Hernas, Adam [Silesian Univ. of Technology, Inst. of Materials Science, Katowice (Poland); Vodarek, Vlastimil [VSB-Technical Univ. of Ostrava (Czech Republic)

    2015-07-15

    Microstructural changes in high alloy (9-12% Cr) creep resistant martensitic X10CrMoVNb9-1 and 12CrMoW . CuVNb steels after 100 000 h of steam exposure at 550 C have been studied using scanning transmission electron microscopy. Precipitates were identified using electron diffraction patterns and energy dispersive X-ray spectroscopy analysis. After long time exposure, a significant coarsening of M{sub 23}C{sub 6} carbides, and intensive precipitation of the coarse Laves phase were observed. Moreover, in the 12CrMoW . CuVNb steel, a low amount of the modified Z-phase particles was detected. The microstructures of the X10Cr . MoVNb9-1 and 12CrMoWCuVNb steels after 100 000 h of exposure differ in several aspects.

  16. ThSi_2 type ytterbium disilicide and its analogues YbT_xSi_2_-_x (T = Cr, Fe, Co)

    International Nuclear Information System (INIS)

    Peter, Sebastian C.; Kanatzidis, Mercouri G.

    2012-01-01

    YbSi_2 and the derivatives YbT_xSi_2_-_x (T = Cr, Fe, Co) crystallizing in the α-ThSi_2 structure type were obtained as single crystals from reactions run in liquid indium. All silicides were investigated by single-crystal X-ray diffraction, I4_1/amd space group and the lattice constants are: a = 3.9868(6) Aa and c = 13.541(3) Aa for YbSi_2, a = 4.0123(6) Aa and c = 13.542(3) Aa for YbCr_0_._2_7Si_1_._7_3, a = 4.0142(6) Aa and c = 13.830(3) Aa for YbCr_0_._7_1Si_1_._2_9, a = 4.0080(6) Aa and c = 13.751(3) Aa for YbFe_0_._3_4Si_1_._6_6, and a = 4.0036(6) Aa, c = 13.707(3) Aa for YbCo_0_._2_1Si_1_._7_9. YbSi_2 and YbT_xSi_2_-_x compounds are polar intermetallics with three-dimensional Si and M (T+Si) polyanion sub-networks, respectively, filled with ytterbium atoms. The degree of substitution of transition metal at the silicon site is signficant and leads to changes in the average bond lengths and bond angles substantially. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Structure and wear behavior of AlCrSiN-based coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Du, Hao [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Ming, E-mail: mchen@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Jun [Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Xiong, Ji [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhao, Haibo [The Analysis and Testing Centre, Sichuan University, Chengdu 610065 (China)

    2016-05-01

    Graphical abstract: - Highlights: • AlCrSiN based coating showed amorphous structure. • AlCrSiN/Me{sub x}N coatings obtained better wear resistance. • Molybdenum and niobium increased the coating hardness and wear resistance. - Abstract: AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC–Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N{sub 2} mixtures. Al{sub 0.6}Cr{sub 0.4}, Al{sub 0.6}Cr{sub 0.3}Si{sub 0.1}, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiN{sub x} peak were formed in the AlCrSiN/Me{sub x}N coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H{sup 3}/E{sup 2} ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  18. Boundary and sub-boundary hardening in tempered martensitic 9Cr steel during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Fujio [National Institute for Materials Science, Sengen, Tsukuba (Japan)

    2010-07-01

    The boundary and sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the boundary and sub-boundary hardening. This improves long-term creep strength of base metal. The enhancement of boundary and sub-boundary hardening is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steel P92. In NIMS 9Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. Newly alloy-designed 9Cr steel with 160 ppm boron and 85 ppm nitrogen exhibits much higher creep rupture strength of base metal than P92 and also no Tpe-IV fracture in welded joints at 650 C. (orig.)

  19. Precipitation of carbides in Cr – Mo – V cast steel after service and regenerative heat treatment

    Directory of Open Access Journals (Sweden)

    G. Golański

    2009-01-01

    Full Text Available The paper presents results of research on precipitation processes in chromium – molybdenum – vanadium cast steel. Theexamined material was the following cast steel grade: L21HMF and G17CrMoV5 – 10 (L17HMF after long-term operation at elevatedtemperatures and after regenerative heat treatment. Identification of precipitates was performed by means of the transmission electronmicroscope using carbon extraction replicas and thin foils. On the basis of identifications it has been proved that in the structure ofinvestigated cast steel grades, degraded by long-term operation, there are a few sorts of carbides with diverse stability, such as: M3C; M2C, M23C6, MC, M7C3. Moreover, the occurrence of compound complexes of precipitates – the so called “H-carbides” – has been revealed. Heat treatment of the examined cast steels contributed to changes in morphology and precipitation type. Whilst in the bainitic structure, obtained through heat treatment, only the occurrence of carbide types, such as: M3C; M23C6 and MC has been noticed.

  20. Complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) cooperate in the binding of hydrolyzed complement factor 3 (C3i) to human B lymphocytes

    DEFF Research Database (Denmark)

    Leslie, Robert Graham Quinton; Prodinger, Wolfgang Maria; Nielsen, Claus Henrik

    2003-01-01

    The C3b-binding receptor, CR1/CD35, supports CR2/CD21-mediated activation of complement by human B lymphocytes, possibly by associating with CR2 to promote or stabilize the binding of hydrolyzed C3 (C3i), the primary component of the AP convertase, C3i-Bb. To evaluate this hypothesis, we examined...... the uptake kinetics and binding equilibria for C3i dimer interaction with human blood cells in the absence and presence of CR1- and CR2-blocking mAb. C3i displayed dual uptake kinetics to B lymphocytes, comprising of rapid binding to CR1 and slower binding to CR2. The forward rate constants (k(1)) for CR1...... and CR2, operating independently, differed ca. 9-fold (k(1)=193+/-9.4 and 22.2+/-6.0 x 10(3) M(-1)s(-1), respectively). Equilibrium binding of C3i to B lymphocytes was also complex, varying in strength by ca. 13-fold over the C3i concentration range examined. The maximum association constant (K(a, max...

  1. Boundary and sub-boundary hardening in high-Cr ferritic steels during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, F. [National Institute for Materials Science (NIMS) (Japan)

    2008-07-01

    The sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the sub-boundary hardening. This improves long-term creep strength. The enhancement of boundary and subboundary hardening by fine distribution of precipitates along boundaries is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steels P92 and P122. In NIMS 9% Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. (orig.)

  2. Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

    Directory of Open Access Journals (Sweden)

    M. Garbiak

    2008-08-01

    Full Text Available The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature range of 700–900oC, a high-silicon G phase was additionally identified. The highest kinetics of the precipitation process was recorded after annealing at the temperatures of 800 and 900oC.

  3. Biferroic LuCrO{sub 3}: Structural characterization, magnetic and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Durán, A., E-mail: dural@cnyn.unam.mx [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800 Ensenada, BC (Mexico); Meza F, C.; Morán, E.; Alario-Franco, M.A. [Departamento de Química Inorgánica y Laboratorio Complutense de Altas Presiones, Facultad de Química, Universidad Complutense de Madrid, EU, 28040 Madrid (Spain); Ostos, C., E-mail: ceostoso@gmail.com [Instituto de Química, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-02-14

    Multiferroic LuCrO{sub 3} perovskite-type structure (Pbnm) obtained via auto-ignition synthesis was characterized by a combination of X-ray diffraction (XRD) and thermogravimetric (TG) techniques, and through magnetization and permittivity measurements. Results showed that amorphous combustion powders were fully transformed to orthorhombic LuCrO{sub 3} structure at 1200 K after the first LuCrO{sub 4} crystallization at 700 K. The magnetic response displays thermal irreversibility between zero-field-cooling and field-cooling condition which is due to spin canted AF switching at 116 K. Accordingly, a hysteresis loop in the M(H) data confirms weak ferromagnetism in LuCrO{sub 3}. On the other hand, the permittivity measurement shows a broad peak transition typical of relaxor-type ferroelectrics transition at ∼450 K. Electrical conductivity increases as temperature increases showing an anomaly around the diffuse phase transition. The diffuse phase transition and the formation of the charge carriers are discussed in terms of a local distortion around the Lu Site. - Highlights: • Multiferroic LuCrO{sub 3} was successfully obtained via auto-ignition synthesis. • Amorphous powder is transformed first to LuCrO{sub 4} (700 K) and next to LuCrO{sub 3} (1100 K). • The CrO{sub 6} octahedra are tilted away and rotates from the ideal octahedral shape. • LuCrO{sub 3} exhibits a canted AFM transition (116 K) and a relaxor ferroelectric behavior. • Tilting and rotation of CrO{sub 6} octahedra influenced transport properties on LuCrO{sub 3}.

  4. Effect of M{sub 3}C on the precipitation behavior of M{sub 23}C{sub 6} phase during early stage of tempering in T91 ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chenxi; Liu, Yongchang; Zhang, Dantian; Ning, Baoqun; Yan, Zesheng [School of Material Science and Engineering, Tianjin Key Laboratory of Advanced Jointing Technology, Tianjin University, Tianjin (China)

    2011-12-15

    Tempered martensitic structure is the service condition of T91 ferritic steel after adopting the austenitizing followed by tempering. Needle-like M{sub 3}C particles are precipitated during air cooling after austenization, while the precipitation of M{sub 3}C is suppressed during the water cooling. The effect of existence of M{sub 3}C on the precipitation behaviors of M{sub 23}C{sub 6} during the early stage of tempering, as nucleation site, number density and size distribution, was investigated by means of TEM observation. The TEM results indicate that, upon the same tempering time, the size of M{sub 23}C{sub 6} is smaller and its number density is higher in the sample pre-existing M{sub 3}C than in the sample without M{sub 3}C. This can be explained that existence of M{sub 3}C results in more M{sub 23}C{sub 6} precipitates forming inside of grain, where a relatively low self-diffusion coefficient of alloy element leads to M{sub 23}C{sub 6} hardly coarsening. However, with the prolongation of tempering time, this effect becomes weaken. Microhardness results indicate that the existence of M{sub 3}C phase results in the increase of hardness after tempering due to the precipitation of finer and denser M{sub 23}C{sub 6} particles. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Mechanical properties and electrical conductivity of Cu-Cr and Cu-Cr-4% SiC nanocomposites for thermo-electric applications

    International Nuclear Information System (INIS)

    Mula, Suhrit; Sahani, Pankajini; Pratihar, S.K.; Mal, Siddhartha; Koch, Carl C.

    2011-01-01

    Highlights: → Ball-milled Cu-Cr and Cu-Cr-SiC nanopowders successfully consolidated by microwave sintering. → Addition of nanosize SiC in Cu-Cr leads to enhanced sintered density, wear and hardness. → A good combination of wear resistance, hardness and electrical conductivity resulted in Cu 94 Cr 6 -4% SiC. → Microwave suscepting SiC particles played a pivotal role in good densification retaining matrix grains 99 Cr 1 , Cu 94 Cr 6 , Cu 99 Cr 1 -4 wt.% SiC and Cu 94 Cr 6 -4 wt.% SiC (average particle size ∼30 nm). The 50 h ball-milled samples were uniaxially pressed, and then pellets were sintered at 800 deg. C, 900 deg. C and 1000 deg. C for a constant soaking period of 30 min by microwave sintering technique. Microstructural characterization was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Sintered compacts resulted a highly densified compacts (∼95% relative density) while retaining ultra-fine grains (100-200 nm) in the matrix. The mechanical properties, namely, hardness and wear resistance, and electrical conductivity of the sintered specimens were also evaluated. The best combination of mechanical properties (e.g. hardness ∼2.4 GPa) and electrical conductivity (60.3% of IACS) were obtained for Cu 94 Cr 6 -4 wt.% SiC sintered at 900 deg. C. This is possibly due to presence of ultra-fine grains in the bulk samples, good densification and proper bonding between particles. The results were analyzed in the light of interactions of microwaves between metallic matrix and microwave susceptive SiC particulates.

  6. Structure and grindability of dental Ti-Cr alloys

    International Nuclear Information System (INIS)

    Hsu, H.-C.; Wu, S.-C.; Chiang, T.-Y.; Ho, W.-F.

    2009-01-01

    The purpose of this study was to investigate the structure and microhardness of a series of binary Ti-Cr alloys with Cr contents up to 30 wt%. In addition, the grindability was also evaluated using an electric dental handpiece with SiC wheels, with the goal of developing a titanium alloy with better mechanical properties and machinability than commercially pure titanium (c.p. Ti), a metal generally considered to be difficult to machine. This study evaluated the phase and structure of Ti-Cr alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. Grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min. Results indicated that the structure of Ti-Cr alloys is sensitive to the Cr content. The cast c.p. Ti has a hexagonal α phase. With 5 wt% Cr, metastable β phase starts to be retained. With Cr contents higher than 10 wt%, the equi-axed β phase is almost entirely retained. In addition, athermal ω phase was found in the Ti-5Cr and Ti-10Cr alloys. The largest quantity of ω phase and highest microhardness were found in Ti-10Cr alloy. The grinding rate of the Ti-Cr alloys showed a similar tendency to the microhardness. The Ti-10Cr alloy exhibited the best grindability, especially at 1000 m/min, which presumably due to the brittle nature of the alloy containing the ω phase in the β matrix.

  7. Development of Cr3C2-25(Ni20Cr) nanostructured coatings

    International Nuclear Information System (INIS)

    Cunha, Cecilio Alvares da

    2012-01-01

    This study is divided in two parts. The first part is about the preparation of nanostructured Cr 3 C 2 -25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr 3 C 2 -25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr 3 C 2 -25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain (ε = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr 3 C 2 -25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation (δH = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation (δC p = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr 3 C 2 -25(Ni20Cr) coatings prepared using the HVOF thermal spray process were determined

  8. Structure determination of two structural analogs, named 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16F2N4S) and 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-chlorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16ClFN4S) by synchrotron X-ray powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gündoğdu, Gülsüm; Aytaç, Sevim Peri; Müller, Melanie; Tozkoparan, Birsen; Kaynak, Filiz Betül

    2017-12-01

    Two novel compounds, 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16F2N4S) (1) and 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-chlorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16ClFN4S) (2), have been designed and synthesized as cytotoxic agents. The compounds were characterized by infrared, proton nuclear magnetic resonance, mass spectral data, elemental analysis and X-ray powder diffraction. The present study comprises spectral data and crystal structures of these novel compounds determined from synchrotron X-ray powder diffraction data. The structure solutions were obtained by simulated annealing. The final structures were achieved by Rietveld refinement using soft restraints for all bond lengths, bond angles, and planar groups. Both compounds crystallize in space grouptype='simple'/>$P\\bar 1$,Z= 2, with the unit-cell parametersa= 6.37433(9),b= 11.3641(2),c= 14.09115(19) Å,α= 80.1740(8)°,β= 85.1164(8)°,γ= 80.9831(10)°,V= 991.55(3) Å3of compound (1) anda= 6.53736(6),b= 11.55725(15),c= 14.01373(13) Å,α= 80.3323(7)°,β= 84.8939(6)°,γ= 79.3954(8)°,V= 1024.08(2) Å3of compound (2). Structural analyses reveal that the title compounds are isostructural.

  9. Creep and Oxidation Behavior of Modified CF8C-Plus with W, Cu, Ni, and Cr

    Science.gov (United States)

    Unocic, Kinga A.; Dryepondt, Sebastien; Yamamoto, Yukinori; Maziasz, Philip J.

    2016-04-01

    The microstructures of modified CF8C-Plus (Fe-19Cr-12Ni-0.4W-3.8Mn-0.2Mo-0.6Nb-0.5Si-0.9C) with W and Cu (CF8CPWCu) and CF8CPWCu enhanced with 21Cr + 15Ni or 22Cr + 17.5Ni were characterized in the as-cast condition and after creep testing. When imaged at lower magnifications, the as-cast microstructure was similar among all three alloys as they all contained a Nb-rich interdendritic phase and Mn-based inclusions. Transmission electron microscopy (TEM) analysis showed the presence of nanoscale Cu-rich nanoprecipitates distributed uniformly throughout the matrix of CF8CPWCu, whereas in CF8CPWCu22/17, Cu precipitates were found primarily at the grain boundaries. The presence of these nanoscale Cu-rich particles, in addition to W-rich Cr23C6, nanoscale Nb carbides, and Z-phase (Nb2Cr2N2), improved the creep strength of the CF8CPWCu steel. Modification of CF8CPWCu with Cr and Ni contents slightly decreased the creep strength but significantly improved the oxidation behavior at 1073 K (800 °C). In particular, the addition of 22Cr and 17.5Ni strongly enhanced the oxidation resistance of the stainless steel resulting in a 100 degrees or greater temperature improvement, and this composition provided the best balance between improving both mechanical properties and oxidation resistance.

  10. Electronic structure and superconductivity of fcc Cr

    International Nuclear Information System (INIS)

    Xu, J.; Freeman, A.J.; Jarlborg, T.; Brodsky, M.B.

    1984-01-01

    Results of self-consistent electronic structure calculations are reported for metastable fcc Cr metal. Unlike the case of bcc Cr which has E/sub F/ at a minimum in the density of states (DOS), the DOS at E/sub F/ in fcc Cr is at a peak making this one of the higher-DOS metals with the fcc structure (e.g., comparable with that of Ni and Pt). A calculated Stoner factor of 0.82 indicates that ferromagnetic ordering is not expected. Calculations of the electron-phonon coupling parameter lambda and superconducting transition temperature T/sub c/ were made using the rigid-ion approximation and strong-coupling theory with various estimates of the (unknown) phonon contribution. We conclude that T/sub c/'sroughly-equal2.5 K are reasonable, although they are substantially smaller than the T/sub c/roughly-equal10 K derived from measurements on Au-Cr-Au sandwiches

  11. A first-principles study on the structural, mechanical, electronic and optical properties of the Cr2(AlxGe1−x)C alloys

    International Nuclear Information System (INIS)

    Zhao-Yong, Jiao; Shu-Hong, Ma; Xiao-Fen, Huang

    2014-01-01

    Highlights: • The structural, mechanical and optical properties of Cr 2 (Al x Ge 1−x )C are studied. • The sound velocity and the Debye temperatures for the Cr 2 (Al x Ge 1−x )C are predicted. • Results classify the Cr 2 (Al x Ge 1−x )C (x ⩽ 0.5) as ductile while (x = 0.75, 1) as brittle. • Cr 2 (Al x Ge 1−x )C are predicted to be promising good coating materials. -- Abstract: According to the new experimentally discovered Cr 2 (Al x Ge 1−x )C (x = 0, 0.25, 0.5, 0.75, 1) alloys, we have studied the structural, mechanical, electronic and optical properties based on the first-principles calculation. Obtained structural parameters and distortion parameters are in good agreement with experimental results. It is shown that all the considered compounds are elastically stable and present results classify the Cr 2 (Al x Ge 1−x )C (x ⩽ 0.5) alloys as ductile while the Cr 2 (Al 0.75 Ge 0.25 )C and Cr 2 AlC as brittle. Electronic and optical properties demonstrate that all the considered M 2 AX compounds have a metallic character, and they are predictive of promising good coating materials

  12. Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

    International Nuclear Information System (INIS)

    Sungkono; Siti Aidah

    2015-01-01

    Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

  13. The role of complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) in promoting C3 fragment deposition and membrane attack complex formation on normal peripheral human B cells

    DEFF Research Database (Denmark)

    Nielsen, Claus Henrik; Pedersen, Morten Løbner; Marquart, Hanne Vibeke Hansen

    2002-01-01

    Normal human B lymphocytes are known to activate the alternative pathway (AP) of complement, leading to C3-fragment deposition and membrane attack complex (MAC) formation. The process is mediated via complement receptor type 2 (CR2, CD21), with complement receptor type 1 (CR1, CD35) playing...... a subsidiary role. In this study, we examine the relative contributions of CR1 and CR2 to the deposition of C3 fragments and MAC on B lymphocytes under circumstances where all complement pathways are operational. C3-fragment deposition and MAC formation were assessed on human peripheral B lymphocytes...... in the presence of 30% autologous serum. Blocking the CR2 ligand-binding site with monoclonal antibody (mAb) FE8 resulted in significant reduction (37.9+/-11.9%) in C3-fragment deposition, whereas MAC formation was only marginally affected (12.1+/-22.2% reduction). Blocking the CR1 binding-site resulted...

  14. Calorimetric Investigation of Thermal Stability of 304H Cu (Fe-17.7Cr-9.3Ni-2.95Cu-0.91Mn-0.58Nb-0.24Si-0.1C-0.12N-Wt Pct) Austenitic Stainless Steel

    Science.gov (United States)

    Tripathy, Haraprasanna; Subramanian, Raju; Hajra, Raj Narayan; Rai, Arun Kumar; Rengachari, Mythili; Saibaba, Saroja; Jayakumar, Tammana

    2016-12-01

    The sequence of phase instabilities that take place in a Fe-17.7Cr-9.3Ni-0.58Nb-2.95Cu-0.12N (wt pct) austenitic stainless steel (304H Cu grade) as a function of temperature has been investigated using dynamic calorimetry. The results obtained from this investigation are supplemented by Thermocalc-based equilibrium and Scheil-Gulliver nonequilibrium solidification simulation. The following phase transformation sequence is found upon slow cooling from liquid: L → L + γ → L + γ + MX → γ + MX + δ → γ +MX + M23C6 → γ + MX + M23C6 + Cu. Under slow cooling, the solidification follows austenite + ferrite (AF) mode, which is in accordance with Thermocalc prediction and Scheil-Gulliver simulation. However, higher cooling rates result in skeletal δ-ferrite formation, due to increased segregation tendency of Nb and Cr to segregate to interdendritic liquid. The solidification mode is found to depend on combined Nb + Cu content. Experimental estimates of enthalpy change associated with melting and secondary phase precipitation are also obtained. In addition a semi-quantitative study on the dissolution kinetics of M23C6 type carbides has also been investigated. The standard solution treatment at 1413 K (1140 °C) is found to be adequate to dissolve both Cu and M23C6 into γ-austenite; but the complete dissolution of MX type carbonitrides occurs near the melting region.

  15. New tetragonal derivatives of cubic NaZn13-type structure: RNi6Si6 compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd–Yb)

    International Nuclear Information System (INIS)

    Pani, M.; Manfrinetti, P.; Provino, A.; Yuan, Fang; Mozharivskyj, Y.; Morozkin, A.V.; Knotko, A.V.; Garshev, A.V.; Yapaskurt, V.O.; Isnard, O.

    2014-01-01

    Novel RNi 6 Si 6 compounds adopt the new CeNi 6 Si 6 -type structure for R=La–Ce (tP52, space group P4/nbm N 125-1) and new YNi 6 Si 6 -type structure for R=Y, Sm, Gd–Yb (tP52, space group P4 ¯ b2N 117) that are tetragonal derivative of NaZn 13 -type structure, like LaCo 9 Si 4 -type. The CeNi 6 Si 6 , GdNi 6 Si 6 , TbNi 6 Si 6 , DyNi 6 Si 6 and HoNi 6 Si 6 compounds are Curie–Weiss paramagnets down to ∼30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi 6 Si 6 does not follow Curie–Weiss law. The DyNi 6 Si 6 shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 μ B /f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi 6 Si 6 with K=[±1/4, ±1/4, 0] wave vector below ∼10 K. - Graphical abstract: Novel (La, Ce)Ni 6 Si 6 compounds adopt the new CeNi 6 Si 6 -type structure and (Y, Sm, Gd–Yb) adopt the new YNi 6 Si 6 -type structure that are tetragonal derivative of NaZn 13 -type structure, like LaCo 9 Si 4 -type. The CeNi 6 Si 6 , GdNi 6 Si 6 , TbNi 6 Si 6 , DyNi 6 Si 6 and HoNi 6 Si 6 compounds are Curie–Weiss paramagnets down to ∼30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi 6 Si 6 with K=[±1/4, ±1/4, 0] wave vector below ∼10 K. Display Omitted - Highlights: • The new (La, Ce)Ni 6 Si 6 compounds adopt the new CeNi 6 Si 6 -type structure. • The new (Y, Sm, Gd–Yb)Ni 6 Si 6 compounds adopt the new YNi 6 Si 6 -type structure. • TbNi 6 Si 6 has square modulated c-collinear antiferromagnetic ordering below ∼10 K

  16. In Situ Spectral Kinetics of Cr(VI) Reduction by c-Type Cytochromes in A Suspension of Living Shewanella putrefaciens 200

    Science.gov (United States)

    Liu, Tongxu; Li, Xiaomin; Li, Fangbai; Han, Rui; Wu, Yundang; Yuan, Xiu; Wang, Ying

    2016-07-01

    Although c-type cytochromes (c-Cyts) mediating metal reduction have been mainly investigated with in vitro purified proteins of dissimilatory metal reducing bacteria, the in vivo behavior of c-Cyts is still unclear given the difficulty in measuring the proteins of intact cells. Here, c-Cyts in living Shewanella putrefaciens 200 (SP200) was successfully quantified using diffuse-transmission UV/Vis spectroscopy due to the strong absorbance of hemes, and the in situ spectral kinetics of Cr(VI) reduction by c-Cyts were examined over time. The reduced product Cr(III) observed on the cell surface may play a role in inhibiting the Cr(VI) reduction and reducing the cell numbers with high concentrations (>200 μM) of Cr(VI) evidenced by the 16S rRNA analysis. A brief kinetic model was established with two predominant reactions, redox transformation of c-Cyts and Cr(VI) reduction by reduced c-Cyts, but the fitting curves were not well-matched with c-Cyts data. The Cr(III)-induced inhibitory effect to the cellular function of redox transformation of c-Cyts was then added to the model, resulting in substantially improved the model fitting. This study provides a case of directly examining the reaction properties of outer-membrane enzyme during microbial metal reduction processes under physiological conditions.

  17. Investigation of structural changes in chiral magnet Cr{sub 1∕3}NbS{sub 2} under application of pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mito, M., E-mail: mitoh@mns.kyutech.ac.jp; Tsuruta, K.; Deguchi, H. [Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Tajiri, T. [Faculty of Science, Fukuoka University, Fukuoka 814-0180 (Japan); Kishine, J. [Graduate School of Arts and Sciences, The Open University of Japan, Chiba 261-8586 (Japan); Inoue, K. [Graduate School of Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Institute for Advanced Materials Research, Hiroshima University, Higashihiroshima 739-8526 (Japan); Center for Chiral Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Kousaka, Y. [Graduate School of Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Center for Chiral Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Nakao, Y. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 229-8558 (Japan); Akimitsu, J. [Graduate School of Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Center for Chiral Science, Hiroshima University, Higashihiroshima 739-8526 (Japan); Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 229-8558 (Japan)

    2015-05-14

    We perform structural analysis experiments on the chiral magnet Cr{sub 1∕3}NbS{sub 2}, in which Cr{sup 3+} ions are inserted between hexagonal NbS{sub 2} layers. The noncentrosymmetrical nature of the inserted Cr{sup 3+} appears as a distorted CrS{sub 6} octahedron. Under the application of hydrostatic pressure, the lattice shrinks significantly along the c-axis rather than the a-axis. However, at a pressure P of approximately 3–4 GPa, a kink in the rate of decrease in the lattice parameters is observed, and the slight movement of a Nb atom along the c-axis brings about a decrease in the distortion of the CrS{sub 6} octahedron. This structural change qualitatively suggests a decrease in the strength of the Dzyaloshinskii-Moriya (D-M) interaction. Under hydrostatic pressure, the magnetic ordering temperature T{sub C} decreases, and dT{sub C}/dP exhibits a slight change at around 3 GPa. A series of experiments indicates that the change in the structural symmetry of the CrS{sub 6} octahedron influences the exchange network between Cr{sup 3+} ions as well as the D-M interaction.

  18. Development of Cr{sub 3}C{sub 2}-25(Ni20Cr) nanostructured coatings; Desenvolvimento de revestimentos nanostruturados de Cr{sub 3}C{sub 2}-25(Ni20Cr)

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Cecilio Alvares da

    2012-07-01

    This study is divided in two parts. The first part is about the preparation of nanostructured Cr{sub 3}C{sub 2}-25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr{sub 3}C{sub 2}-25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain ({epsilon} = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation ({delta}H = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation ({delta}C{sub p} = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr{sub 3}C{sub 2}-25(Ni20Cr) coatings

  19. Immune cells from SR/CR mice induce the regression of established tumors in BALB/c and C57BL/6 mice

    DEFF Research Database (Denmark)

    Koch, Janne; Hau, Jann; Pravsgaard Christensen, Jan

    2013-01-01

    of resistance to EL-4 lymphoma cells and J774A.1 monocyte-macrophage cancer cells. The cancer resistance against S180 sarcoma cells could be transferred to susceptible non-resistant BALB/c mice as well as C57BL/6 mice after depletion of both CD4+/CD8+ leukocytes and B-cells from SR/CR mice. In the responding...

  20. Influence of Heat Treatment on the Microstructure and Corrosion Resistance of 13 Wt Pct Cr-Type Martensitic Stainless Steel

    Science.gov (United States)

    Lu, Si-Yuan; Yao, Ke-Fu; Chen, Yun-Bo; Wang, Miao-Hui; Ge, Xue-Yuan

    2015-12-01

    The effect of heat treatment on the microstructure and the electrochemical properties of a typical corrosion-resistant plastic mold steel in Cl--containing solution were studied in this research. Through X-ray diffraction patterns, SEM and TEM analysis, it was found that the sequence of the precipitates in the steels tempered at 573 K, 773 K, and 923 K (300 °C, 500 °C, and 650 °C) was θ-M3C carbides, nano-sized Cr-rich M23C6 carbides, and micro/submicron-sized Cr-rich M23C6 carbides, respectively. The results of the electrochemical experiments showed that the pitting potential of the as-quenched martensitic stainless steels increased with the austenitizing temperature. However, the corrosion resistance of the steels would decreased after tempering, especially when tempered at 773 K (500 °C), no passivation regime could be found in the polarization curve of the MSSs and no effective passive film could be formed on the steels in Cl--containing environments. The present results suggested that the temperature around 773 K (500 °C) should be avoided for tempering process of MSS used as plastic molds.

  1. STRUCTURAL STABILITY OF HIGH NITROGEN AUSTENITIC STAINLESS STEELS

    Directory of Open Access Journals (Sweden)

    Jana Bakajová

    2011-05-01

    Full Text Available This paper deals with the structural stability of an austenitic stainless steel with high nitrogen content. The investigated steel was heat treated at 800°C using different annealing times. Investigation was carried out using light microscopy, transmission electron microscopy and thermodynamic calculations. Three phases were identified by electron diffraction: Cr2N, sigma – phase and M23C6. The thermodynamic prediction is in good agreement with the experimental result. The only is the M23C6 carbide phase which is not thermodynamically predicted. Cr2N is the majority secondary phase and occurs in the form of discrete particles or cells (lamellas of Cr2N and austenite.

  2. Structural, mechanical and corrosion studies of Cr-rich inclusions in 152 cladding of dissimilar metal weld joint

    Science.gov (United States)

    Li, Yifeng; Wang, Jianqiu; Han, En-Hou; Yang, Chengdong

    2018-01-01

    Cr-rich inclusions were discovered in 152 cladding at the inner wall of domestic dissimilar metal weld joint, and their morphologies, microstructures, mechanical properties and corrosion behaviors were systematically characterized by SEM, TEM, nanoindentation and FIB. The results indicate that the Cr-rich inclusions originate from large-size Cr particles in 152 welding electrode flux, and they are 50-150 μm in size in most cases, and there is a continuous transition zone of 2-5 μm in width between the Cr inclusion core and 152 cladding matrix, and the transition zone consists of Ni & Fe-rich dendritic austenite and Cr23C6 and Cr matrix. The transition zone has the highest nanoindentation hardness (7.66 GPa), which is much harder than the inclusion core (5.14 GPa) and 152 cladding (3.71 GPa). In-situ microscopic tensile tests show that cracks initialize preferentially in transition zone, and then propagate into the inclusion core, and creep further into 152 cladding after penetrating the core area. The inclusion core and its transition zone both share similar oxide film structure with nickel-base 152 cladding matrix in simulated primary water, while those two parts present better general corrosion resistance than 152 cladding matrix due to higher Cr concentration.

  3. Effective Management of Hexavalent Chromium (Cr+6) in DoD Organic and Inorganic Coatings Operations

    Science.gov (United States)

    2014-11-19

    results confirm Cr6+ to Cr3+ reductions at expected levels • Additional dwell time and saturated cloth wipes expected to increase efficiency and...Stress crazing of MIL-PRF-5425 and MIL-PRF-25690 (Type A and C) acrylic plastics 3.10 Stress crazing of polycarbonate plastics 3.11 Long term storage...Spent Plating Solution Extractant with Iron Purified Plating Solution Recycle of iron-laden stripping solution Selective Extraction of Iron

  4. Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Liuyang Fang

    2017-12-01

    Full Text Available The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS2, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD, scanning electron microscopy (SEM, and energy dispersive spectrometer (EDS, as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS2 and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr23C6, and CoCx. Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS2 were 587.3 HV0.5, 0.426, and 5.61 × 10−5 mm3/N·m, respectively.

  5. Research on the hot deformation behavior of a Fe-Ni-Cr alloy (800H) at temperatures above 1000 °C

    Science.gov (United States)

    Cao, Yu; Di, Hongshuang

    2015-10-01

    Considering the pinning effect of fine carbides on grain boundaries, hot compression tests were performed above the dissolution temperature of Cr23C6 to investigate the hot deformation behavior of a Fe-Ni-Cr alloy (800H). The results show that the single peak stress associated with dynamic recrystalization (DRX) became more distinct at higher temperature and lower strain rate. The process of DRX was thoroughly stimulated when deformed above 1000 °C. Constitutive equations for hot deformation were established by regression analysis of conventional hyperbolic sine equation. The relationships between Zener-Hollomon parameter (Z) and the characteristic points of flow curves were established using the power law relation. Furthermore, kernel average misorientation (KAM) and grain orientation spread (GOS) were used to map the distribution of local misorientation and estimate the fraction of DRX, respectively. The critical strain and peak strain were used to predict the kinetics of DRX with the Avrami-type equation.

  6. Structure and physical properties of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Fang; Forbes, Scott [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Ramachandran, Krishna Kumar [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

    2015-11-25

    The Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} phase was prepared by arc-melting, while the Cr{sub 5}B{sub 3}-type Ta{sub 5}Ge{sub 3} one was synthesized through sintering at 1000 °C. X-ray single crystal diffraction was employed to elucidate their structure. According to the magnetization measurements, both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} are Pauli paramagnets, with Ta{sub 5}Ge{sub 3} showing a Curie-Weiss-like paramagnetic behavior at low temperatures likely due to presence of paramagnetic impurity. Both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} display a very low electrical resistivity from 2 to 300 K. The resistivity is constant below 20 K, but displays a positive temperature coefficient above 20 K. Electronic structure calculations with the TB-LMTO-ASA method support the metallic character of the two phases and suggest that the bonding is optimized in both phases. - Highlights: • Synthesis of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases with high purity by arc-melting and sintering, respectively. • Magnetization data and electrical resistivity of the Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases. • Crystal and electronic structure analysis for Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phase by X-ray diffraction and TB-LMTO-ASA calculations.

  7. Gas sensing behaviour of Cr{sub 2}O{sub 3} and W{sup 6+}: Cr{sub 2}O{sub 3} nanoparticles towards acetone

    Energy Technology Data Exchange (ETDEWEB)

    Kohli, Nipin, E-mail: nipinkohli82@yahoo.com; Hastir, Anita; Singh, Ravi Chand [Department of Physics, Guru Nanak Dev University, Amritsar-143005 (India)

    2016-05-23

    This paper reports the acetone gas sensing properties of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} nanoparticles. The simple cost-effective hydrolysis assisted co-precipitation method was adopted. Synthesized samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. XRD revealed that synthesized nanoparticles have corundum structure. The lattice parameters have been calculated by Rietveld refinement; and strain and crystallite size have been calculated by using the Williamson-Hall plots. For acetone gas sensing properties, the nanoparticles were applied as thick film onto alumina substrate and tested at different operating temperatures. The results showed that the optimum operating temperature of both the gas sensors is 250°C. At optimum operating temperature, the response of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} gas sensor towards 100 ppm acetone was found to be 25.5 and 35.6 respectively. The investigations revealed that the addition of W{sup 6+} as a dopant enhanced the sensing response of Cr{sub 2}O{sub 3} nanoparticles appreciably.

  8. Alloy Design of Martensitic 9Cr-Boron Steel for A-USC Boiler at 650 °C — Beyond Grades 91, 92 and 122

    Science.gov (United States)

    Abe, Fujio; Tabuchi, M.; Tsukamoto, S.

    Boundary hardening is shown to be the most important strengthening mechanism in creep of tempered martensitic 9% Cr steel base metal and welded joints at 650 °C. The enrichment of soluble boron near prior austenite grain boundaries (PAGBs) by the GB segregation is essential for the reduction of coarsening rate of M23C6 carbides near PAGBs, enhancing the boundary and sub-boundary hardening near PAGBs, and also for the change in α/γ transformation behavior in heat-affected-zone (HAZ) of welded joints during heating of welding, producing the same microstructure in HAZ as in the base metal. Excess addition of nitrogen to the 9Cr-boron steel promotes the formation of boron nitrides during normalizing heat treatment, which consumes most of soluble boron and degrades the creep strength. A NIMS 9Cr steel (MARBN; Martensitic 9Cr steel strengthened by boron and MX nitrides) with 120-150 ppm boron and 60-90 ppm nitrogen, where no boron nitride forms during normalizing heat treatment, exhibits not only much higher creep strength of base metal than Grades 91, 92 and 122 but also substantially no degradation in creep strength due to Type IV fracture in HAZ of welded joints at 650°C. The protective Cr2O3-rich scale forms on the surface of 9Cr steel by pre-oxidation treatment in Ar gas, which significantly improves the oxidation resistance in steam at 650°C.

  9. A Convenient Approach to Heterocyclic Building Blocks: Synthesis of Novel Ring Systems Containing a [5,6]Pyrano[2,3-c]pyrazol-4(1H-one Moiety

    Directory of Open Access Journals (Sweden)

    Wolfgang Holzer

    2007-01-01

    Full Text Available Starting from commercially available educts, a straightforward synthetic route to new heterocyclic building blocks is exemplified with the one- or two-step synthesis of tri-, tetra-, or pentacyclic ring systems. Representatives of the following novel ring systems are prepared from 3-methyl-1-phenyl-2-pyrazolin-5-one and the corresponding o-halo-arenecarbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane: pyrimidino[4',5':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3',2':5,6]pyrano[2,3c]pyrazol- 4-(1H-one, thieno[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3'',2'':4',5']thieno[2',3':5,6]-pyrano[2,3-c]pyrazol-4(1H-one, [1,3]dioxolo[5',6'][1]benzothieno[2',3':5,6]pyrano-[2,3-c]- pyrazol-4(1H-one, pyridazino[4',3':5,6]pyrano[2,3-c]pyrazol-4(1H-one and pyrazolo-[4'',3'':5',6']pyrido[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one. While the latter two ring systems are directly obtained due to a spontaneous intramolecular substitution reaction, in the other reactions uncyclised 4-aroylpyrazol-5-ols are produced, which are cyclised into the target heterocycles in a subsequent synthetic step (i.e. treatment with NaH in DMF. Detailed NMR spectroscopic investigations (1H-, 13C-, 15N- with the obtained compounds were undertaken to unambiguously prove the new structures.

  10. RDT&E Progress and Plansfor Hexavalent Chromium (Cr6+)

    Science.gov (United States)

    2011-05-12

    RDT&E Progress and Plans for Hexavalent Chromium (Cr6+) Bruce Sartwell Weapons Systems and Platforms Program Manager E2S2 Conference May 12, 2011...2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE RDT&E Progress and Plansfor Hexavalent Chromium (Cr6+) 5a...Development of Accelerated Corrosion Test Protocols Alternatives to Hex Chrome and Cadmium Plating Alternatives to Hex Chrome Pretreatments

  11. Detection of Hydrogen Sulphide Gas Sensor Based Nanostructured Ba2CrMoO6 Thick Films

    Directory of Open Access Journals (Sweden)

    A. V. Kadu

    2007-11-01

    Full Text Available Nanocrystalline pure and doped Ba2CrMoO6, having an average crystallite size of 40 nm were synthesized by the sol-gel citrate method. Structural and gas-sensing characteristics were performed by using X-ray diffraction (XRD and sensitivity measurements. The gas sensing properties to reducing gases like Hydrogen sulphide (H2S, liquefied petroleum gas (LPG, carbon monoxide (CO and hydrogen gas (H2 were also discussed. The maximum sensitivity was obtained for 5 wt % Ni doped Ba2CrMoO6 at an operating temperature 250oC for H2S gas. Pd incorporation over 5 wt% Ni doped Ba2CrMoO6 improved the sensitivity, selectivity, response time, and reduced the operating temperature from 250 to 200oC of the sensor for H2S gas. This sensor also shows good satiability.

  12. Comparison between lactulose/mannitol and 51Cr-ethylenediaminetetraacetic acid/14C-mannitol methods for intestinal permeability

    International Nuclear Information System (INIS)

    Blomquist, L.; Bark, T.; Hedenborg, G.; Svenberg, T.; Norman, A.

    1993-01-01

    Urinary excretion of lactulose and mannitol, determined by gas-liquid chromatography, was compared with that of 51 Cr-ethylenediaminetetraacetic acid (EDTA) and 14 C-mannitol for measurement of intestinal permeability in 28 healthy humans. The 0- to 6-h excretion values for unlabelled and labelled mannitol (marker of transcellular permeability) were normally distributed, whereas excretion values for lactulose and 51 Cr-EDTA (markers of paracellular permeability) were shewly distributed, as were the lactulose to mannitol and 51 Cr-EDTA to 14 C-mannitol ratios. Excretion of the transcellular markers, but not of the paracullular markers was significantly correlated to urinary volume; correction for urinary volume resulted in decreased test variability. Significant correlation was found between lactulose and 51 Cr-EDTA excretion and between mannitol and 14 C-mannitol excretion, but not between the lactulose to mannitol and 51 Cr-EDTA to 14 C-mannitol ratios. Inter- and intraindividual test variability was greater for each chemically determined marker than for the corresponding isotope-labelled marker. Similarly, variability was greater for each paracellular marker than for the corresponding transcellular marker and for each paracellular/transcellular marker ratio, than for the transcellular marker alone. Variability of mannitol excretion was increased by the frequent presence of food-derived mannitol in the urine. 23 refs., 5 figs., 2 tabs

  13. Gas6 Promotes Inflammatory (CCR2hiCX3CR1lo) Monocyte Recruitment in Venous Thrombosis.

    Science.gov (United States)

    Laurance, Sandrine; Bertin, François-René; Ebrahimian, Talin; Kassim, Yusra; Rys, Ryan N; Lehoux, Stéphanie; Lemarié, Catherine A; Blostein, Mark D

    2017-07-01

    Coagulation and inflammation are inter-related. Gas6 (growth arrest-specific 6) promotes venous thrombosis and participates to inflammation through endothelial-innate immune cell interactions. Innate immune cells can provide the initiating stimulus for venous thrombus development. We hypothesize that Gas6 promotes monocyte recruitment during venous thrombosis. Deep venous thrombosis was induced in wild-type and Gas6-deficient (-/-) mice using 5% FeCl 3 and flow reduction in the inferior vena cava. Total monocyte depletion was achieved by injection of clodronate before deep venous thrombosis. Inflammatory monocytes were depleted using an anti-C-C chemokine receptor type 2 (CCR2) antibody. Similarly, injection of an anti-chemokine ligand 2 (CCL2) antibody induced CCL2 depletion. Flow cytometry and immunofluorescence were used to characterize the monocytes recruited to the thrombus. In vivo, absence of Gas6 was associated with a reduction of monocyte recruitment in both deep venous thrombosis models. Global monocyte depletion by clodronate leads to smaller thrombi in wild-type mice. Compared with wild type, the thrombi from Gas6 -/- mice contain less inflammatory (CCR2 hi CX 3 CR1 lo ) monocytes, consistent with a Gas6-dependent recruitment of this monocyte subset. Correspondingly, selective depletion of CCR2 hi CX 3 CR1 lo monocytes reduced the formation of venous thrombi in wild-type mice demonstrating a predominant role of the inflammatory monocytes in thrombosis. In vitro, the expression of both CCR2 and CCL2 were Gas6 dependent in monocytes and endothelial cells, respectively, impacting monocyte migration. Moreover, Gas6-dependent CCL2 expression and monocyte migration were mediated via JNK (c-Jun N-terminal kinase). This study demonstrates that Gas6 specifically promotes the recruitment of inflammatory CCR2 hi CX 3 CR1 lo monocytes through the regulation of both CCR2 and CCL2 during deep venous thrombosis. © 2017 American Heart Association, Inc.

  14. TEM characterization of a Cr/Ti/TiC graded interlayer for magnetron-sputtered TiC/a-C:H nanocomposite coatings

    International Nuclear Information System (INIS)

    Galvan, D.; Pei, Y.T.; De Hosson, J.Th.M.

    2005-01-01

    A TiC/a-C:H nanocomposite coating is deposited on top of a Cr/Ti/TiC graded interlayer. Cross-section transmission electron microscopy is employed to investigate the detailed structure of the interlayer and the coating. Five different phases are formed as a consequence of the compositional gradient within the interlayer: pure Cr, a solid solution of Ti in Cr, a Ti/Cr amorphous/nanocrystalline phase, α-Ti and TiC. Solid state amorphization occurs during the interlayer deposition to give a dispersion of TiCr β-phase nanocrystals in an amorphous matrix. The TiC phase is textured and contains numerous stacking faults as a result of the growth in under-stoichiometric carbon concentration. C-enriched columnar boundaries are present within the coating, originating from the TiC column boundaries of the interlayer. The work indicates that an interlayer of amorphous/nanocrystalline Ti/Cr phase would reduce the presence of growth defects such as columnar boundaries within nanocomposite TiC/a-C:H coatings

  15. Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

    Science.gov (United States)

    Kano, Sho; Yang, Huilong; Shen, Jingjie; Zhao, Zishou; McGrady, John; Hamaguchi, Dai; Ando, Mamami; Tanigawa, Hiroyasu; Abe, Hiroaki

    2018-04-01

    In order to clarify the instability of M23C6 in F82H steel under irradiation, both electron irradiation using a high voltage electron microscope (HVEM) and ion irradiation using an ion accelerator were performed. For the electron irradiation, in-situ observation under 2 MV electron irradiation and ex-situ high resolution electron microscopic (HREM) analysis were utilized to evaluate the response of M23C6 against irradiation. The temperature dependence of the irradiation induced instability of the carbide was first confirmed: 293 K indicating severe loss of crystallinity due to dissolution of the constituent atoms though irradiation-enhanced diffusion under the vacancy diffusion by the focused electron beam irradiation. For the ion irradiation, 10.5 MeV-Fe3+ ion was applied to bombard the F82H steel at 673 K to achieve the displacement damage of ≈20 dpa at the depth of 1.0 μm from surface. Cross-section TEM specimens were prepared by a focused ion beam technique. The shrinkage of carbide particles was observed especially near the irradiation surface. Besides, the lattice fringes at the periphery of carbide were observed in the irradiated M23C6 by the HREM analysis, which is different from that observed in the electron irradiation. It was clarified that the instability of M23C6 is dependent on the irradiation conditions, indicating that the flow rate of vacancy type defects might be the key factor to cause the dissolution of constituent atoms of carbide particles into matrix under irradiation.

  16. First-principles study on the structure, elastic properties, hardness and electronic structure of TMB4 (TM=Cr, Re, Ru and Os) compounds

    International Nuclear Information System (INIS)

    Pan, Y.; Zheng, W.T.; Guan, W.M.; Zhang, K.H.; Fan, X.F.

    2013-01-01

    The structural formation, elastic properties, hardness and electronic structure of TMB 4 (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C 22 for these compounds is almost two times bigger than the C 11 and C 33 . The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB 4 >ReB 4 >RuB 4 >OsB 4 , and the Poisson's ratio and B/G ratio of TMB 4 follow the order of CrB 4 4 4 4 . The intrinsic hardness of CrB 4 and ReB 4 by LDA is bigger than 40 GPa. The high hardness of TMB 4 compounds is derived from the feature of B–B bonds cage and higher C 22 value. The B–B covalent bonds as bonds cage enhances the resistance to shear deformation and improve the hardness. We predict that the TMB 4 compounds with CrB 4 -type are the potential superhard materials. - Graphical abstract: The first-principles calculations show that the intrinsic hardness of CrB 4 and ReB 4 are bigger than 40 GPa, which are the potential superhard materials due to the B–B bonds cage structure. Display Omitted - Highlights: • The intrinsic hardness of CrB 4 and ReB 4 is bigger than 40 GPa. • The hardness of TMB 4 is calculated to be in a sequence of CrB 4 >ReB 4 >RuB 4 >OsB 4 . • The trend of hardness for TMB 4 is consistent with the variation of elastic modulus. • The C 22 value of TMB 4 is bigger than that of C 11 and C 33 . • The high hardness of TMB 4 is originated from the B–B bonds cage

  17. Effect of tungsten content on the microstructure and tensile properties of Ni–xW–6Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shulin [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ye, Xiang-Xi, E-mail: yexiangxi@sinap.ac.cn [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Jiang, Li [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Cui, Chuanyong [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Zhijun, E-mail: lizhijun@sinap.ac.cn [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Huang, Hefei; Leng, Bin [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhou, Xingtai, E-mail: zhouxingtai@sinap.ac.cn [Center for Thorium Molten Salt Reactor System, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-02-08

    Ni–xW–6Cr alloys have been considered as one of the potential structural materials for molten salt techniques, whereas their microstructure and mechanical performance have not been sufficiently studied. In this study, the microstructure and tensile deformation behavior of Ni–(10–35 wt%)W–6Cr alloys have been systematically investigated. The phase diagram calculations indicated that the solubility limit of W is 34 wt% in Ni–xW–6Cr alloy. α-W phase is formed in the matrix while the W content exceeds such limit. The fracture of the Ni–(10–35 wt%)W–6Cr alloys at room temperature is in the transgranular ductile fracture mode. The tensile properties of alloys, except for the elongation of Ni–35 wt%W–6Cr alloy, are improved with the increase of W content, which can be explained by the larger lattice distortion, the lower stack fault energy and the higher length fraction of twin boundaries (Σ3 and Σ9 type) in the Ni–(10–35 wt%)W–6Cr alloys caused by the addition of more W. The reduced elongation of the Ni–35 wt%W–6Cr alloy is ascribed to the particles in α-W phase which act as the main nucleation sites for cracking.

  18. Synthesis of (Cr,V){sub 2}(C,N) solid solution powders by thermal processing precursors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Anrui [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China); Liu, Ying [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China); Key Laboratory of Advanced Special Material & Technology, Ministry of Education, Chengdu, 610065 (China); Ma, Shiqing; Qiu, Yuchong; Rong, Pengcheng; Ye, Jinwen [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China)

    2017-06-01

    The single-phase (Cr,V){sub 2}(C,N) solid solution powders were fabricated via carbothermal reduction-nitridation (CRN) processing technique. The effects of heat treatment temperature, nitrogen pressure and carbon proportion were experimentally studied in detail by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and thermal analysis. The chemical transformations of vanadium and chromium compounds were as follows: precursors → V{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} → Cr{sub 3}C{sub 2}, Cr{sub 2}O{sub 3}, (Cr,V){sub 2}(C,N) → (Cr,V){sub 2}(C,N). When the heat-treated temperature was below 1200 °C, chromium oxides didn’t completely react. However, higher temperature ∼1300 °C could not only lead to the segregation of some nitrides and carbon black, but also to the occurrence of fiber-bridged particles. The system nitrogen pressure over 0.03 MPa would cause a subtle transformation of (Cr,V){sub 2}(C,N) to VCrN{sub 2}. When the carbon proportion was below 15 wt%, the oxides could not be completely reduced, while when the carbon proportion was above 15.5 wt%, some undesired carbides, like Cr{sub 23}C{sub 6} and Cr{sub 3}C{sub 2}, would form. Ultimately, the homogeneously distributed pure-phase (Cr,V){sub 2}(C,N) spherical particles with the average size of ∼1.5 μm were obtained at the optimal conditions of the treatment of precursors at 1200 °C for 1 h with the nitrogen pressure of 0.03 MPa and carbon content of 15.5 wt%. The chemical composition of the solid solution with the optimal process could be drawn as (Cr{sub 0.85}V{sub 0.15}){sub 2}(C{sub 0.57}N{sub 0.43}). Thermal processing precursors method shows the advantages of lower synthesis temperature, shorter period and finer particles when comparing with the conventional preparations. - Highlights: • Single phase of (Cr,V){sub 2}(C,N) powders were synthesized for the first time. • Precursors were used to prepared the powders by carbothermal

  19. Creep strength and microstructure in 23Cr-45Ni-7W Alloy (HR6W) and Ni-base superalloys for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Semba, Hiroyuki; Okada, Hirokazu; Yonemura, Mitsuharu; Igarashi, Masaaki [Sumitomo metal Industries, Ltd., Hyogo (Japan). Corporate Research and Development Labs.

    2008-07-01

    Establishment of materials technologies on piping and tubing for advanced ultra super critical (A-USC) plants operated at steam temperatures above 700 C is a critical issue to achieve its hard target. 23Cr-45Ni-7W alloy (HR6W) has been developed in Japan, originally as a high strength tubing material for 650 C USC boilers. In order to clarify the capability of HR6W as a material applied to A-USC plants, creep strength and microstructure of HR6W were investigated in comparison with {gamma}'-strengthened Alloy 617 and other Ni-base superalloys, such as Alloy 263. It has been revealed that the amount of added W is intimately correlated with precipitation amount of Laves phase and thus it is a crucial factor controlling creep strength. Stability of long term creep strength and superior creep rupture ductility have been proved by creep rupture tests at 650-800 C up to 60000h. The 10{sup 5}h extrapolated creep rupture strengths are estimated to be 88MPa at 700 C and 64MPa at 750 C. Microstructural stability closely related with long term creep strength and toughness has also been confirmed by microstructural observations after creep tests and aging. Creep rupture strength of Alloy 617 has been found to be much higher than that of HR6W at 700 and 750 C, while comparable at 800 C. A thermodynamic calculation along with microstructural observation indicates that the amount of Laves phase in HR6W gradually decreases with increasing temperature, while that of {gamma}' in Alloy 617 rapidly decreases with increasing temperature and {gamma}' almost dissolves at 800 C. This may lead to an abrupt drop in creep strength of Alloy 617 above 750 C. Alloy 263, in which more {gamma}' precipitates than Alloy 617, shows much higher creep strength. However, it is suggested that inhomogeneous creep deformation is enhanced compared with HR6W and Alloy 617. Capability of HR6W as a material for A-USC plants was discussed in terms of creep properties, microstructural stability and other

  20. Kinetics of Cr/Mo-rich precipitates formation for 25Cr-6.9Ni-3.8Mo-0.3N super duplex stainless steel

    Science.gov (United States)

    Byun, Sang-Ho; Kang, Namhyun; Lee, Tae-Ho; Ahn, Sang-Kon; Lee, Hae Woo; Chang, Woong-Seong; Cho, Kyung-Mox

    2012-04-01

    The amount and composition of Cr-rich (σ) and Mo-rich (χ) precipitates in super duplex stainless steels was analyzed. An isothermal heat treatment was conducted at temperatures ranging from 700 °C to 1000 °C for up to 10 days. A time-temperature transformation (TTT) diagram was constructed for the mixture of σ and χ phases. The mixture of the σ and χ phases exhibited the fastest rate of formation at approximately 900 °C. Minor phases, such as Cr2N, M23C6, and M7C3, were also detected using a transmission electron microscopy (TEM). Also, a continuous cooling transformation (CCT) diagram was constructed for the mixture of σ and χ phases using the Johnson-Mehl-Avrami equation. Compared with the known CCT diagram of the σ phase, this study revealed faster kinetics with an order of magnitude difference and a new CCT diagram was also developed for a mixture of σ and χ phases. The calculated fraction of σ and χ phases obtained at a cooling speed of 0.5 °C/s was in good agreement with the experimental data.

  1. Structural, magnetic, and dielectric properties of multiferroic Co1−xMgxCr2O4 nanoparticles

    International Nuclear Information System (INIS)

    Kamran, M.; Ullah, A.; Rahman, S.; Tahir, A.; Nadeem, K.; Anis ur Rehman, M.; Hussain, S.

    2017-01-01

    Highlights: • Properties of multiferroic Co 1−x Mg x Cr 2 O 4 nanoparticles have been studied. • XRD showed that CoCr 2 O 4 and MgCr 2 O 4 are cubic normal spinel structure. • Rietveld refinement of XRD showed no impurity phases. • T c and T s showed decreasing trend with increasing Mg concentration. • Dielectric properties were improved for x = 0.6 Mg concentration. - Abstract: We examined the structural, magnetic, and dielectric properties of Co 1−x Mg x Cr 2 O 4 nanoparticles with composition x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1 in detail. X-ray diffraction (XRD) revealed normal spinel structure for all the samples. Rietveld refinement fitting results of the XRD showed no impurity phases which signifies the formation of single phase Co 1−x Mg x Cr 2 O 4 nanoparticles. The average crystallite size showed a peak behaviour with maxima at x = 0.6. Raman and Fourier transform infrared (FTIR) spectroscopy also confirmed the formation of single phase normal spinel for all the samples and exhibited dominant vibrational changes for x ≥ 0.6. For x = 0 (CoCr 2 O 4 ), zero field cooled/field cooled (ZFC/FC) magnetization curves showed paramagnetic (PM) to ferrimagnetic (FiM) transition at T c = 97 K and a conical spiral magnetic order at T s = 30 K. The end members CoCr 2 O 4 (x = 0) and MgCr 2 O 4 (x = 1) are FiM and antiferromagnetic (AFM), respectively. T c and T s showed decreasing trend with increasing x, followed by an additional AFM transition at T N = 15 K for x = 0.6. The system finally stabilized and changed to highly frustrated AFM structure at x = 1 due to formation of pure MgCr 2 O 4 . High field FC curves (5T) depicted nearly no effect on spiral magnetic state, which is attributed to strong exchange B-B magnetic interactions at low temperatures. Dielectric parameters showed a non-monotonous behaviour with Mg concentration and were explained with the help of Maxwell-Wagner model and Koop’s theory. Dielectric properties were improved for

  2. The SNARE protein SNAP23 and the SNARE-interacting protein Munc18c in human skeletal muscle are implicated in insulin resistance/type 2 diabetes

    DEFF Research Database (Denmark)

    Boström, Pontus; Andersson, Linda; Vind, Birgitte

    2010-01-01

    /cytosolic compartment in the patients with the type 2 diabetes. Expression of the SNARE-interacting protein Munc18c was higher in skeletal muscle from patients with type 2 diabetes. Studies in L6 cells showed that Munc18c promoted the expression of SNAP23. CONCLUSIONS: We have translated our previous in vitro results......OBJECTIVE: Our previous studies suggest that the SNARE protein synaptosomal-associated protein of 23 kDa (SNAP23) is involved in the link between increased lipid levels and insulin resistance in cardiomyocytes. The objective was to determine whether SNAP23 may also be involved in the known...... association between lipid accumulation in skeletal muscle and insulin resistance/type 2 diabetes in humans, as well as to identify a potential regulator of SNAP23. RESEARCH DESIGN AND METHODS: We analyzed skeletal muscle biopsies from patients with type 2 diabetes and healthy, insulin-sensitive control...

  3. Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding.

    Science.gov (United States)

    Fang, Liuyang; Yan, Hua; Yao, Yansong; Zhang, Peilei; Gao, Qiushi; Qin, Yang

    2017-12-28

    The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS₂, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS₂ and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr 23 C₆, and CoC x . Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS₂) were 587.3 HV 0.5 , 0.426, and 5.61 × 10 -5 mm³/N·m, respectively.

  4. High Rate Deposition of Thick CrN and Cr2N Coatings Using Modulated Pulse Power (MPP) Magnetron Sputtering

    Science.gov (United States)

    2010-12-01

    AISI 440C steel using a microtribometer (Center for Tribology , Inc) in an ambient air atmosphere without a lubricant (a relative humidity of 251...that the CTE for the 440 C stainless steel substrate is 10.2x10 -6 o C -1 [37],while the CTE values for the CrN and Cr2N coatings are 2.3x10 -6...increased scratch critical load (Fig. 12) as the coating thickness was increased. Since the coating is much harder than the stainless steel substrate

  5. Microstructural evolution in austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during long-term service

    International Nuclear Information System (INIS)

    Liu Jiangwen; Jiao Dongling; Luo Chengping

    2010-01-01

    The microstructural evolution of austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during aging and long-term service was investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructure of the as cast steel consists of the dendritic austenite, the block-like eutectic carbide M 7 C 3 spreaded among austenitic dendrite, and a small quantity of M 23 C 6 carbide. The microstructure of the steel aged at 600 deg. C consists of eutectic carbide M 23 C 6 transformed from eutectic carbide M 7 C 3 and dendritic austenite in which fine secondary carbide particles M 23 C 6 precipitated. The precipitated carbide M 23 C 6 kept a cubic-cubic orientation relationship (OR) with austenite matrix. There existed a carbide precipitation free zone (PFZ) around the eutectic carbide. For the long-term serviced samples, the secondary carbide precipitated in the austenite strikingly increased and the PFZ disappeared. Part of the M 23 C 6 transformed into M 6 C, which always kept a twin OR, [114] M 6 C //[110] A //[110] M 23 C 6 , with the austenite and the M 23 C 6 secondary carbide. In addition, a small quantity of σ phase FeCr and ε-Cr 2 N were also identified. The effects of alloy composition and service condition on the microstructural evolution of the steel were discussed.

  6. System Ba/sub 2/Gdsub(2/3)vacantsub(1/3)Usub(1-x)Wsub(x)O/sub 6/ and hexagonal perovskites of an 18-layer type

    Energy Technology Data Exchange (ETDEWEB)

    Wischert, W; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-04-01

    In the system Ba/sub 2/Gdsub(2/3)vacantsub(1/3)Usub(1-x)Wsub(x)O/sub 6/ the formation of a continuous solid solution series is observed. With x <= 0.9 the mixed crystals have a cubic 1:1 ordered perovskite structure. With x >= 0.95 the compounds are polymorphic: besides an cubic 1:1 ordered perovskite type for x = 0.95; 0.99 and 1.00 one hexagonal layer structure exists. This lattice is in all cases rhombohedral (space group R3m) and represents an 18 L-type. Likewise the compounds Ba/sub 2/Bsub(2/3)sup(III)vacantsub(1/3)Wsup(VI)O/sub 6/ with Bsup(III) Tb-Lu and Y belong to the 18 L-type.

  7. New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub 6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd–Yb)

    Energy Technology Data Exchange (ETDEWEB)

    Pani, M.; Manfrinetti, P.; Provino, A. [INFM and Dipartimento di Chimica e Chimica Industriale, Universita‘ di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4M1 (Canada); Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V.; Garshev, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Isnard, O. [Université Grenoble Alpes, Inst NEEL, BP166, F-38042 Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, F-38042 Grenoble (France)

    2014-02-15

    Novel RNi{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure for R=La–Ce (tP52, space group P4/nbm N 125-1) and new YNi{sub 6}Si{sub 6}-type structure for R=Y, Sm, Gd–Yb (tP52, space group P4{sup ¯}b2N 117) that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ∼30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi{sub 6}Si{sub 6} does not follow Curie–Weiss law. The DyNi{sub 6}Si{sub 6} shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 μ{sub B}/f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ∼10 K. - Graphical abstract: Novel (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure and (Y, Sm, Gd–Yb) adopt the new YNi{sub 6}Si{sub 6}-type structure that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ∼30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ∼10 K. Display Omitted - Highlights: • The new (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure. • The new (Y, Sm, Gd–Yb)Ni{sub 6}Si{sub 6} compounds adopt the new YNi{sub 6}Si{sub 6}-type structure. • TbNi{sub 6}Si

  8. Hardness and Wear Resistance of TiC-Fe-Cr Locally Reinforcement Produced in Cast Steel

    Directory of Open Access Journals (Sweden)

    Olejnik E.

    2016-06-01

    Full Text Available In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.

  9. Aging of a cast 35Cr-45Ni heat resistant alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sustaita-Torres, Ireri A., E-mail: ireri.sustaita@gmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Haro-Rodriguez, Sergio, E-mail: haros907@hotmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Guerrero-Mata, Martha P., E-mail: martha.guerreromt@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Garza, Maribel de la, E-mail: maribeldelagarza@yahoo.com.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Valdes, Eduardo, E-mail: eduardo.valdes.57@gmail.com [Instituto Tecnologico de Saltillo, 25280 Saltillo (Mexico); Deschaux-Beaume, Frederic, E-mail: deschaux@iut-nimes.fr [Mechanical and Civil Engineering Laboratories, Universite de Montpellier 2, IUT Nimes, 30907 Nimes (France); and others

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer The as-cast microstructure is made of an austenitic matrix and primary carbides. Black-Right-Pointing-Pointer The carbides are of two different types: Cr- and Nb-rich. Black-Right-Pointing-Pointer The microstructure changes during aging. Black-Right-Pointing-Pointer These microstructural changes result in the degradation of mechanical properties. - Abstract: The microstructural evolution during aging and its effect on the mechanical properties of a centrifugally cast 35Cr-45Ni heat resistant alloy was studied by means of optical and electron microscopy, and by mechanical testing in samples aged in air at 750 Degree-Sign C for a period of time of up to 1000 h. The as-cast microstructure consisted of an austenitic matrix and a network of two types of primary carbides that were identified as NbC and M{sub 7}C{sub 3} by their light and dark tones when viewed in backscattered electron mode in a scanning electron microscope. Aging promoted the occurrence of different phenomena such as the transformation of primary M{sub 7}C{sub 3} to M{sub 23}C{sub 6} carbides, precipitation of secondary M{sub 23}C{sub 6} carbides and the transformation of NbC to Nb{sub 3}Ni{sub 2}Si. It was found that aging promoted an increase in Vickers microhardness of more than 50%, the increment in tensile strength of around 20% and the reduction in ductility of close to 70%.

  10. First-principle study of structural, electronic and magnetic properties of (FeC)n (n = 1-8) and (FeC)8TM (TM = V, Cr, Mn and Co) clusters.

    Science.gov (United States)

    Li, Cheng-Gang; Zhang, Jie; Zhang, Wu-Qin; Tang, Ya-Nan; Ren, Bao-Zeng; Hu, Yan-Fei

    2017-12-13

    The structural, electronic and magnetic properties of the (FeC) n (n = 1-8) clusters are studied using the unbiased CALYPSO structure search method and density functional theory. A combination of the PBE functional and 6-311 + G* basis set is used for determining global minima on potential energy surfaces of (FeC) n clusters. Relatively stabilities are analyzed via computing their binding energies, second order difference and HOMO-LUMO gaps. In addition, the origin of magnetic properties, spin density and density of states are discussed in detail, respectively. At last, based on the same computational method, the structures, magnetic properties and density of states are systemically investigated for the 3d (V, Cr, Mn and Co) atom doped (FeC) 8 cluster.

  11. Quasicrystalline and crystalline phases in Al65Cu20(Fe, Cr)15 alloys

    International Nuclear Information System (INIS)

    Liu, W.; Koester, U.; Mueller, F.; Rosenberg, M.

    1992-01-01

    Two types of icosahedral quasicrystals are observed in Al 65 Cu 20 Fe 15-x Cr x (0 ≤ x ≤ 15) alloys, the face-centred AlCuFe-type icosahedral phase with dissoluted Cr and the primitive AlCuCr-type icosahedral phase with dissoluted Fe. In the vicinity of Al 65 Cu 20 Fe 8 Cr 7 a stable decagonal phase (a=0.45 nm and c=1.23 nm) forms competitively with the icosahedral quasicrystals. All these three quasicrystalline phases can be regarded as Hume-Rothery phases stabilized by the energy band factor. The density is measured to be 4.57, 4.44, and 4.11 g/cm 3 for the icosahedral Al 65 Cu 20 Fe 15 , the decagonal Al 65 Cu 20 Fe 8 Cr 7 , and the icosahedral Al 65 Cu 20 Cr 15 alloys, respectively. Depending on the composition in the range between Al 65 Cu 20 Fe 8 Cr 7 and Al 65 Cu 20 Cr 15 , several crystalline phases are observed during the transormation of the AlCuCr-type icosahedral phase: the 1/1-3/2-type orthorhombic (o) and the 1/0-3/2-type tetragonal (t) approximants of the decagonal phase, a hexagonal (h) phase, as well as a long-range vacancy ordered τ 3 -phase derived from a CsCl-type structure with a=0.2923 nm. The structures of all the crystalline phases are closely related to those of the icosahedral (i) and decagonal (d) quasicrystals, which leads to a definite orientation relationship as follows: i5 parallel d10 parallel o[100] parallel t[100] parallel h[001] parallel τ 3 [110]. (orig.)

  12. Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings

    Directory of Open Access Journals (Sweden)

    Aleksei Obrosov

    2017-02-01

    Full Text Available MAX phases (M = transition metal, A = A-group element, and X = C/N are of special interest because they possess a unique combination of the advantages of both metals and ceramics. Most attention is attracted to the ternary carbide Cr2AlC because of its excellent high-temperature oxidation, as well as hot corrosion resistance. Despite lots of publications, up to now the influence of bias voltage on the chemical bonding structure, surface morphology, and mechanical properties of the film is still not well understood. In the current study, Cr-Al-C films were deposited on silicon wafers (100 and Inconel 718 super alloy by dc magnetron sputtering with different substrate bias voltages and investigated using Scanning Electron Microscopy (SEM, X-ray Photoelectron Spectroscopy (XPS, X-ray Diffraction (XRD, Atomic Force Microscopy (AFM, and nanoindentation. Transmission Electron Microscopy (TEM was used to analyze the correlation between the growth of the films and the coating microstructure. The XPS results confirm the presence of Cr2AlC MAX phase due to a negative shift of 0.6–0.9 eV of the Al2p to pure aluminum carbide peak. The XRD results reveal the presence of Cr2AlC MAX Phase and carbide phases, as well as intermetallic AlCr2. The film thickness decreases from 8.95 to 6.98 µm with increasing bias voltage. The coatings deposited at 90 V exhibit the lowest roughness (33 nm and granular size (76 nm combined with the highest hardness (15.9 GPa. The ratio of Al carbide to carbide-like carbon state changes from 0.12 to 0.22 and correlates with the mechanical properties of the coatings. TEM confirms the columnar structure, with a nanocrystalline substructure, of the films.

  13. Microstructure and wear behavior of stellite 6 cladding on 17-4 PH stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Gholipour, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shamanian, M., E-mail: shamanian@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ashrafizadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-04-07

    Research highlights: > The microstructure of the surface layer consisted of carbides embedded in a Co-rich solid solution with dendritic structure. Primary phases formed during the process were identified as Co(FCC) and lamellar eutectic phases (M{sub 23}C{sub 6}, M{sub 6}C, Cr{sub 7}C{sub 3}). > Microhardness profiles showed that hardness increases from interface to the coating surface. This is due to the finer size of the grains at coating surface in comparison to that at interface and also diffusion of Fe adjacent to the interface. > The delamination was suggested as the dominant mechanism of the wear. In this regard, plate-like wear debris consisted of voids and cracks. In addition, due to increase in surface temperature, Cr{sub 2}O{sub 3} oxide phase was formed during wear tests. - Abstract: This paper deals with the investigation of the microstructure and wear behavior of the stellite 6 cladding on precipitation hardening martensitic stainless steel (17-4PH) using gas tungsten arc welding (GTAW) method. 17-4 PH stainless steel is widely used in oil and gas industries. Optical metallography, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to study the microstructure and wear mechanisms. X-ray diffraction analysis was also used to identify phases formed in the coating. The results showed that the microstructure of the surface layer consisted of carbides embedded in a Co-rich solid solution with a dendritic structure. In addition, the dendritic growth in the coating was epitaxial. Primary phases formed during the process were Co (fcc), Co (hcp), lamellar eutectic phases, M{sub 23}C{sub 6} and Cr{sub 7}C{sub 3} type carbides. The results of the wear tests indicated that the delamination was the dominant mechanism. So, it is necessary to apply an inter-layer between the substrate and top coat.

  14. Synthesis, structure and electronic configuration of [Rh{sub 6}Te{sub 8}(PPh{sub 3}){sub 6}].4C{sub 6}H{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, Guenther; Balmer, Markus [Marburg Univ. (Germany). Fachbereich Chemie; Dehnen, Stefanie [Marburg Univ. (Germany). Fachbereich Chemie and Wissenschaftliches Zentrum fuer Materialwissenschaften

    2016-08-01

    [Rh{sub 6}Te{sub 8}(PPh{sub 3}){sub 6}].4C{sub 6}H{sub 6}, the first compound with a molecular Chevrel-type [Rh{sub 6}Te{sub 8}] cluster core has been synthesized and structurally characterized. By means of quantum chemical calculation, the close relationship of its electronic configuration to that of the lighter homologue has been demonstrated. The different crystal solvent content prevents an isostructural crystallization.

  15. At last! The single-crystal X-ray structure of a naturally occurring sample of the ilmenite-type oxide FeCrO3.

    Science.gov (United States)

    Pérez-Cruz, María Ana; Elizalde-González, María de la Paz; Escudero, Roberto; Bernès, Sylvain; Silva-González, Rutilo; Reyes-Ortega, Yasmi

    2015-10-01

    A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R3̅. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3 (hematite) and Cr2O3 (eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3 [Sadat Nabi & Pentcheva (2011). Phys. Rev. B, 83, 214424], and suggest that synthetic samples of FeCrO3 might present a cation distribution different to that of the ilmenite structural type.

  16. High-pressure BaCrO_3 polytypes and the 5H–BaCrO_2_._8 phase

    International Nuclear Information System (INIS)

    Arévalo-López, Angel M.; Paul Attfield, J.

    2015-01-01

    Polytypism of BaCrO_3 perovskites has been investigated at 900–1100 °C and pressures up to 22 GPa. Hexagonal 5H, 4H, and 6H perovskites are observed with increasing pressure, and the cubic 3C perovskite (a=3.99503(1) Å) is observed in bulk form for the first time at 19–22 GPa. An oxygen-deficient material with limiting composition 5H–BaCrO_2_._8 is synthesised at 1200 °C under ambient pressure. This contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure. - Graphical abstract: Hexagonal 5H, 4H, and 6H perovskites polytypes of BaCrO_3 are observed with increasing pressure and the cubic 3C perovskite is stabilised in bulk form for the first time at 19–22 GPa. Oxygen-deficient 5H–BaCrO_2_._8 synthesised at ambient pressure contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure.

  17. Calculations of spin Hamiltonian parameters and analysis of trigonal distortions in LiSr(Al,Ga)F6:Cr3+ crystals

    International Nuclear Information System (INIS)

    Brik, M.G.; Avram, C.N.; Avram, N.M.

    2006-01-01

    The effective spin-Hamiltonian (SH) parameters (zero-field splitting D and g factors g - parallel and g - perpendicular ) for Cr 3+ ions in LiSr(Al,Ga)F 6 crystals are calculated from the complete high-order perturbation formulae for a d 3 ion. Parameters of trigonal crystal field acting on the Cr 3+ ion are calculated. The magnitude of trigonal distortion of the [CrF 6 ] 3- clusters is related to the experimental measurements of the spin-Hamiltonian parameters in the considered systems. Since in both crystals g parallel perpendicular , [CrF 6 ] 3- clusters undergo an axial compression along the C 3 axis. Experimental values of the hyperfine structure constants A parallel and A perpendicular are used to evaluate the core polarization constant κ for Cr 3+ ion in both crystals

  18. Crystal structures of lazulite-type oxidephosphates TiIIITiIV3O3(PO4)3 and MIII4TiIV27O24(PO4)24 (MIII=Ti, Cr, Fe)

    International Nuclear Information System (INIS)

    Schoeneborn, M.; Glaum, R.; Reinauer, F.

    2008-01-01

    Single crystals of the oxidephosphates Ti III Ti IV 3 O 3 (PO 4 ) 3 (black), Cr III 4 Ti IV 27 O 24 (PO 4 ) 24 (red-brown, transparent), and Fe III 4 Ti IV 27 O 24 (PO 4 ) 24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti III Ti IV 3 O 3 (PO 4 ) 3 : Z=24, a=7.3261(9) A, b=22.166(5) A, c=39.239(8) A, R 1 =0.029, wR 2 =0.084, 6055 independent reflections, 301 variables; Cr III 4 Ti IV 27 O 24 (PO 4 ) 24 : Z=1, a=7.419(3) A, b=21.640(5) A, c=13.057(4) A, R 1 =0.037, wR 2 =0.097, 1524 independent reflections, 111 variables; Fe III 4 Ti IV 27 O 24 (PO 4 ) 24 : Z=1, a=7.4001(9) A, b=21.7503(2) A, c=12.775(3) A, R 1 =0.049, wR 2 =0.140, 1240 independent reflections, 112 variables). For Ti III Ti IV O 3 (PO 4 ) 3 a well-ordered structure built from dimers [Ti III,IV 2 O 9 ] and [Ti IV,IV 2 O 9 ] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr 4 Ti 27 O 24 (PO 4 ) 24 and Fe 4 Ti 27 O 24 (PO 4 ) 24 , consisting of dimers [M III Ti IV O 9 ] and [Ti IV,IV 2 O 9 ], monomeric [Ti IV O 6 ] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti III 4 Ti IV 27 O 24 (PO 4 ) 24 (a=7.418(2) A, b=21.933(6) A, c=12.948(7) A) is isotypic to the oxidephosphates M III 4 Ti IV 27 O 24 (PO 4 ) 24 (M III : Cr, Fe). The UV/vis spectrum of Cr 4 Ti 27 O 24 (PO 4 ) 24 reveals a rather small ligand-field splitting Δ o =14,370 cm -1 and a very low nephelauxetic ratio β=0.72 for the chromophores [Cr III O 6 ] within the dimers [Cr III Ti IV O 9 ]. - Graphical abstract: Single crystals of the oxidephosphates Ti III Ti IV 3 O 3 (PO 4 ) 3 (black), Cr III 4 Ti IV 27 O

  19. Domain structures and temperature-dependent spin reorientation transitions in c-axis oriented Co-Cr thin films

    International Nuclear Information System (INIS)

    Kusinski, Greg J.; Krishnan, Kannan M.; Thomas, Gareth; Nelson, E. C.

    2000-01-01

    Highly c-axis oriented Co 95 Cr 5 films with perpendicular anisotropy were grown epitaxially on Si (111), using an Ag seed layer, by physical vapor deposition. Films were characterized by x-ray diffraction, transmission electron microscopy (TEM), selected area electron diffraction, and Lorentz microscopy in a TEM. The following epitaxial relationship was confirmed: (111) Si (parallel sign)(111) Ag (parallel sign)(0001) CoCr ;[2(bar sign)20] Si (parallel sign)[2(bar sign)20] Ag (parallel sign)[1(bar sign)100] CoCr . Magnetic domain structures of these films were observed as a function of thickness; t, in the range, 200 Aa c ≅300 Aa, the magnetization was found to be effectively in-plane of the film, and above t c a regular, stripe-like domain pattern with a significant, alternating in sign, perpendicular component was observed. The spin reorientation transitions of the stripe domains to the in-plane magnetization were studied dynamically by observing the domains as a function of temperature by in situ heating up to 350 degree sign C. The critical transition thickness, t c , which is a function of K u and magnetostatic energy, was found to increase with increasing temperature. The stripe-domain period, L observed at room temperature was found to increase gradually with thickness; L=90 nm at t=300 Aa, and L=110 nm at t=700 Aa. (c) 2000 American Institute of Physics

  20. Effect of heat treatment and irradiation temperature on mechanical properties and structure of reduced-activation Cr-W-V steels of bainitic, martensitic, and martensitic-ferritic classes

    International Nuclear Information System (INIS)

    Gorynin, I.V.; Rybin, V.V.; Kursevich, I.P.; Lapin, A.N.; Nesterova, E.V.; Klepikov, E.Yu.

    2000-01-01

    Effects of molybdenum replacement by tungsten in steels of the bainitic, martensitic, and martensitic-ferritic classes containing 2.5%, 8% and 11% Cr, respectively, were investigated. The phase composition and structure of the bainitic steels were varied by changing the cooling rates from the austenitization temperature (from values typical for normalization up to V=3.3 x 10 -2 deg. C/s) and then tempering. The steels were irradiated to a fluence of 4x10 23 n/m 2 (≥0.5 MeV) at 270 deg. C and to fluences of 1.3x10 23 and 1.2x10 24 n/m 2 (≥0.5 MeV) at 70 deg. C. The 2.5Cr-1.4WV and 8Cr-1.5WV steels have shown lower values of the shifts in ductile-brittle transition temperature (DBTT) under irradiation in comparison with corresponding Cr-Mo steels. Radiation embrittlement at elevated irradiation temperature was lowest in bainitic 2.5Cr-1.4WV steel and martensitic-ferritic 11Cr-1.5WV steel. The positive effect of molybdenum replacement by tungsten at irradiation temperature ∼300 deg. C is reversed at T irr =70 deg. C

  1. Surface stabilized GMR nanorods of silver coated CrO2 synthesized via a polymer complex at ambient pressure

    Science.gov (United States)

    Biswas, S.; Singh, G. P.; Ram, S.; Fecht, H.-J.

    2013-08-01

    Stable anisotropic nanorods of surface modified CrO2 (˜18 nm diameter) with a correlated diamagnetic layer (2-3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr4+ ions by Ag atoms on the CrO2 surface (topotactic surface layer) via an etching reaction of a CrO2-polymer complex with Ag+ ions in hot water followed by heating the dried sample at 300-400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO2 such that it no longer converts to Cr2O3 in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO2 structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d5/2 and 3d3/2 X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (-) 7.6% at 77 K, than reported values in compacted CrO2 powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO2 nanorods.

  2. Structure and delayed failure behaviour of 0.25C-Ni-Cr-Mo-V steel

    International Nuclear Information System (INIS)

    Kang, C.H.; Maeng, S.C.

    1980-01-01

    Delayed failure behaviour of the different transformation structures of 0.25C-2.5Ni-2.5Cr-0.5Mo-0.1V low alloy steel has been studied. The studied microstructures are martensite, lower bainite, and mixed structure of 50% martensite and 50% lower bainite. All these structures have been tempered at 450 deg C for 40 min to have the same tensile strength level of 143 kg/mm 2 . Delayed failure testing has been carried out with cantilever bend tester, in distilled water at 25 deg C. By comparing K 1 sub(scc) values, lower bainitic structure has shown the highest value, although it is only slightly higher than that of the martensitic structure. Mixed structure has the lowest resistance to delayed failure. The fracture modes of both martensitic and mixed structures have been observed as intergranular. In the martensitic structure, however, it is noticeable that there is a larger amount of ductile tearing between intergranular facets. The fracture mode of lower bainitic structure is the mixed topography of microplastic tearing and microvoid coalescence. The above experimental results are discussed in terms of Oriani's decohesion theory of hydrogen embrittlement. The lowest resistance of the mixed structure to delayed failure may be due to the enhanced decohesion by hydrogen at the phase boundaries of martensite and lower bainite. (author)

  3. Electronic Structure of Eu6C60

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Xiong; LI Hong-Nian; XU Ya-Bo; WANG Peng; ZHANG Wen-Hua; XU Fa-Qiang

    2009-01-01

    We study the valence band of Eu-intercalated C60 by synchrotron radiation photoelectron spectroscopy to un-derstand the ferromagnetism (FM) and the giant magnetoresistance (GMR) of Eu6C60. The results reveal the semiconducting property and the remarkable 5d6s-π hybridization. Eu-C60 bonding has both ionic and covalent contributions. No more than half the 5d6s electrons transfer from Eu to the LUMO derived band of C60, and the LUMO+1 derived band is not filled. The remaining valence electrons of Eu, together with some π (LUMO, HOMO and HOMO-1) electrons, constitute the covalent bond. The electronic structure implies that the magnetic coupling in Eu6C60 should be through the intra-atomic f-sd exchange and the medium of the π electrons. The possibility of the GMR being tunnelling magnetoresistance is ruled out.

  4. Structure and magnetism in Cr-embedded Co nanoparticles.

    Science.gov (United States)

    Baker, S H; Kurt, M S; Roy, M; Lees, M R; Binns, C

    2016-02-03

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core.

  5. Effects of Fe and Cr on corrosion behavior of ZrFeCr alloys in 500 oC steam

    International Nuclear Information System (INIS)

    Wang Jun; Fan Hongyuan; Xiong Ji; Liu Hong; Miao Zhi; Ying Shihao; Yang Gang

    2011-01-01

    Research highlights: Amount and size of SPP will effect the corrosion resistance of Zr alloy at 500 o C/10.3 MPa. - Abstract: A study of the corrosion behaviors of ZrFeCr alloy and the influence of microstructure on corrosion resistance are described by X-ray diffraction and scanning electron microscope in this paper. The results show that several ZrFeCr alloys exhibit protective behavior throughout the test and oxide growth is stable and protective. The best alloy has the composition Zr1.0Fe0.6Cr. Fitting of the weight gain curves for the protective oxide alloys in the region of protective behavior, it showed nearly cubic behavior for the most protective alloys. The Zr1.0Fe0.6Cr has the more laves Zr(Fe,Cr) 2 precipitate in matrix and it has the better corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, the biggest hydrogen absorption and the worst corrosion resistance. The number of precipitates and the amount of hydrogen absorption in Zr alloy plays an important role on corrosion resistance behaviors in 500 o C/10.3 MPa steam.

  6. Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy

    Science.gov (United States)

    Harf, F. H.; Tewari, S. N.

    1977-01-01

    Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.

  7. Ethylene polymerization by PN3-type pincer chromium(III) complexes

    KAUST Repository

    Gong, Dirong

    2014-12-01

    Chromium (III) complexes, Cr1, [2,6-(tBu2PNH) 2C5H4N]CrCl3; Cr2, [2,6-(Ph 2PNH)2C5H4N]CrCl3; Cr3, [2-(tBu2PNH)C5H4N]CrCl3 THF; Cr4, [6-(tBu2PNH)C5H4N-2- CH2NEt2]CrCl3; Cr5, [6-(tBu 2PNH)C5H4N-2-C3H2N 2]CrCl3; Cr6, [6-(tBu2PNH)C 5H4N-2-(3,5-Me2)C3H 2N2]CrCl3; Cr7, [6-(tBu 2PNH)C5H4N-2-(3,5-iPr 2)C3H2N2]CrCl3; Cr8, [6-(tBu2PNH)C5H4N-2-(3,5-Ph 2)C3H2N2]CrCl3, bearing a family of neutral PN3-type pincer ligands have been prepared. The molecular structure of Cr2 was further elucidated by the X-ray crystallographic analysis, showing an octahedral geometry. Treatment of these complexes with MAO or alkylaluminum led to catalysts with moderate activities (about 105 g (PE)/Cr(mol) h) for ethylene polymerization, affording exclusively linear low molecular weight solid PE without any detectable oligomers. Among Cr1-Cr8, the highest activity was achieved for Cr1/MAO at room temperature with production of PE with highest molecular weight, indicating that replacement of both tBu groups in Cr1 with Ph groups, or one PtBu2 with the N (imine) arm, resulted in a lower catalytic activity and lower M w. © 2014 Elsevier B.V.

  8. Sintering behaviour and mechanical properties of Cr3C2–NiCr ...

    Indian Academy of Sciences (India)

    fracture toughness. Keywords. Cermet; Cr3C2–NiCr; sintering; mechanical properties. ... et al investigated the mechanical properties of VC, Cr3C2 and NbC doped ..... Huang S G, Li L, Van der Biest O and Vleugels J 2008 J. Alloys. Compds.

  9. Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

    KAUST Repository

    Wang, Hao; Dong, Xinglong; Lin, Junzhong; Teat, Simon J.; Jensen, Stephanie; Cure, Jeremy; Alexandrov, Eugeny V.; Xia, Qibin; Tan, Kui; Wang, Qining; Olson, David H.; Proserpio, Davide M.; Chabal, Yves J.; Thonhauser, Timo; Sun, Junliang; Han, Yu; Li, Jing

    2018-01-01

    As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr6O4(OH)4(bptc)3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr6O4(OH)8(H2O)4(abtc)2, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.

  10. Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

    KAUST Repository

    Wang, Hao

    2018-04-25

    As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr6O4(OH)4(bptc)3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr6O4(OH)8(H2O)4(abtc)2, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.

  11. Reduced-activation austenitic stainless steels: The Fe--Mn--Cr--C system

    International Nuclear Information System (INIS)

    Klueh, R.L.; Maziasz, P.J.

    1988-01-01

    Nickel-free manganese-stabilized steels are being developed for fusion-reactor applications. As the first part of this effort, the austenite-stable region in the Fe--Mn--Cr--C system was determined. Results indicated that the Schaeffler diagram developed for Fe--Ni--Cr--C alloys cannot be used to predict the constituents expected for high-manganese steels. This is true because manganese is not as strong an austenite stabilizer relative to δ-ferrite formation as predicted by the diagram, but it is a stronger austenite stabilizer relative to martensite than predicted. Therefore, the austenite-stable region for Ne--Mn--Cr--C alloys occurs at lower chromium and hugher combinations of manganese and carbon than predicted by the Schaeffler diagram. Development of a manganese-stabilized stainless steel should be possible in the composition range of 20 to 25% Mn, 10 to 15% Cr, and 0.01 to 0.25%C. Tensile behavior of an Fe--20%Mn--12%Cr--0.25%C alloy was determined. The strength and ductility of this possible base composition was comparable to type 316 stainless steel in both the solution-annealed and cold-worked condition

  12. Crystal Structure of Na3MoCl6

    Directory of Open Access Journals (Sweden)

    Martin Beran

    2011-07-01

    Full Text Available The ternary chloride Na3MoCl6 is obtained as red crystals from a disproportionation reaction of molybdenum dichloride, {Mo6}Cl12, in an acidic NaCl/AlCl3 melt at 350 °C. The crystal structure (trigonal, P-31c, a = 687.1(1, c = 1225.3(2 pm, Z = 2, V = 501,0(1 106 pm3 is that of Na3CrCl6: within a hexagonal closest-packing of chloride ions two thirds of the octahedral voids are filled between the AB double layers with Na+/Mo3+, and between the BA layers with Na+.

  13. Pressure-induced changes in Cr3+-doped elpasolites and LiCaAlF6: Interpretation of macroscopic data

    DEFF Research Database (Denmark)

    Trueba, A. ,; García Lastra, Juan Maria; Aramburu, J. A.

    2010-01-01

    In the research of pressure effects on Cr3+-doped insulating lattices, it is crucial to understand the dependence of the 10Dq parameter on the sample volume, V. This problem is explored in the present work through ab initio calculations on Cr3+-doped K2NaScF6, Cs2NaYCl6, and Cs2NaYBr6 elpasolite...... dependence on V−m/3 for LiCaAlF6:Cr3+ where the measured exponent m=2.3 is seemingly anomalous when compared to the values found for ruby (m=4.5) or NiO (m=5)....

  14. Microstructure Evolution of Electron Beam Physical Vapour Deposited Ni-23.5Cr-2.66Co-1.44Al Superalloy Sheet During Annealing at 600 °C

    Directory of Open Access Journals (Sweden)

    Li Mingwei

    2013-02-01

    Full Text Available Microstructure evolution of electron beam physical vapour deposited (EB-PVD Ni‑23.5Cr‑2.66Co‑1.44Al superalloy sheet during annealing at 600 °C was investigated. The results showed that the as-deposited alloy was composed of only g phase. After annealing at 600 °C, the locations of diffraction peaks were still the same. The (220 diffraction peak of the deposition side increased with annealing time. The sheet on deposited side had a tendency toward forming (220 texture during post-annealing. No obvious texture was observed at as-deposited and annealed sheet at 600 °C in substrate side. The count and size of "voids" decreased with time. The size of grains increased obviously with annealing time. The ultimate tensile strength of EB-PVD Ni-23.5Cr-2.66Co-1.44Al alloy sheet increased from 641 MPa to 829 MPa after annealing at 600 °C for 30 hours.

  15. First-principles study on the structure, elastic properties, hardness and electronic structure of TMB{sub 4} (TM=Cr, Re, Ru and Os) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Y. [Department of Materials Science, Key Laboratory of Automobile Materials of MOE and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Zheng, W.T., E-mail: WTZheng@jlu.edu.cn [Department of Materials Science, Key Laboratory of Automobile Materials of MOE and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Guan, W.M.; Zhang, K.H. [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming 650106 (China); Fan, X.F. [Department of Materials Science, Key Laboratory of Automobile Materials of MOE and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

    2013-11-15

    The structural formation, elastic properties, hardness and electronic structure of TMB{sub 4} (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C{sub 22} for these compounds is almost two times bigger than the C{sub 11} and C{sub 33}. The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB{sub 4}>ReB{sub 4}>RuB{sub 4}>OsB{sub 4}, and the Poisson's ratio and B/G ratio of TMB{sub 4} follow the order of CrB{sub 4}CrB{sub 4} and ReB{sub 4} by LDA is bigger than 40 GPa. The high hardness of TMB{sub 4} compounds is derived from the feature of B–B bonds cage and higher C{sub 22} value. The B–B covalent bonds as bonds cage enhances the resistance to shear deformation and improve the hardness. We predict that the TMB{sub 4} compounds with CrB{sub 4}-type are the potential superhard materials. - Graphical abstract: The first-principles calculations show that the intrinsic hardness of CrB{sub 4} and ReB{sub 4} are bigger than 40 GPa, which are the potential superhard materials due to the B–B bonds cage structure. Display Omitted - Highlights: • The intrinsic hardness of CrB{sub 4} and ReB{sub 4} is bigger than 40 GPa. • The hardness of TMB{sub 4} is calculated to be in a sequence of CrB{sub 4}>ReB{sub 4}>RuB{sub 4}>OsB{sub 4}. • The trend of hardness for TMB{sub 4} is consistent with the variation of elastic modulus. • The C{sub 22} value of TMB{sub 4} is bigger than that of C{sub 11} and C{sub 33}. • The high hardness of TMB{sub 4} is originated from the B–B bonds cage.

  16. EPR, mu-Raman and Crystallographic properties of spinel type ZnCr{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Hernandez, C; Almanza, O; Jurado, J F, E-mail: cvargash@unal.edu.c [Universidad Nacional de Colombia, Manizales-Colombia Laboratorio de Propiedades Opticas de Materiales-POM (Colombia)

    2009-05-01

    Structural, vibrational and electron paramagnetic resonance (EPR) analysis for compound ZnCr{sub 2}O{sub 4} are shown in this work. These types of materials are used in technological applications as humidity sensors and piezoelectric devices. The compound was obtained by mean of solid state reaction technique from binary precursors ZnO and Cr{sub 2}O{sub 3}. After three thermal treatments the sample structure was monitoring using X ray diffraction (XRD), the spinel cubic phase has been indexed within O{sup 7}{sub h}(Fd3m) spatial group. It is observed normal spinel phase. Micro-Raman analysis revealed bands for normal vibration modes of Zn and Cr atoms in tetrahedral and octahedral environments formed by oxygen atoms at approximately 400 and 900 cm{sup -1}, respectively. Bands around 941 cm{sup -1} are associated possibly to vacancies in the tetrahedral and octahedral sites due to interaction between Zn and Cr ions. EPR signal from 150 to 300 K isothermals indicates a transition between inverse spinel to normal spinel type in a central field around 3350 G. A signal at approximately 3400 G corresponding to the C'r{sup +3} in tetrahedral sites is observed near the central field.

  17. Effect of heat treatment on the microstructure of Co-Cr-W alloy fabricated by laser additive manufacturing

    Science.gov (United States)

    Ren, Bo; Chen, Changjun; Zhang, Min

    2018-04-01

    Stellite 6 cobalt-based alloy powder was used to produce Co-Cr-W alloy using laser additive manufacturing technology, and then different heat treatment strategies were carried out on the deposited sample. The characteristics of microstructure under different heat treatment conditions were investigated using scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscope, and x-ray diffraction. The results show that the as-deposited sample has few cracks or pores, and the microstructure is typical dendritic structure, and lamellar eutectic carbides are rich in Cr in interdendritic. The matrix mainly consists of γ phases and a few ɛ phases. Some γ phases transform into ɛ phases after 900°C/6 h aging treatment and lamellar eutectic carbides transform into blocky carbides presenting as a network, most of the carbides are rich in Cr and a few are rich in W. When heat treated at 1200°C/1 h followed by water cooling and then treated at 900°C/6 h followed by furnace cooling, it can be found that some γ phases transform into ɛ phases. The carbides transform into elliptical M23C6 carbides that are rich in Cr with the size of 1 to 3 μm and a part of W-rich carbides.

  18. On the knowledge of the (NH4)3SiF7 type of structure

    International Nuclear Information System (INIS)

    Hofmann, B.; Hoppe, R.

    1979-01-01

    New obtained are Rb 3 SiF 7 (a = 7.95 9 ; c = 5.82 3 A), Cs 3 SiF 7 (a = 8.30 6 ; c = 6.17 0 A), Rb 3 TiF 7 (a = 8.20 2 ; c = 5.97 9 A), Cs 3 TiF 7 (a = 8.47 3 ; c = 6.31 3 A). and Cs 2 RbSiF 7 (a = 8.19 8 ; c = 6.01 9 A); Cs 2 KSiF 7 (a = 8.11 5 , c = 5.97 2 A), Rb 2 CsSiF 7 (a = 8.09 9 ; c = 5.89 9 A), Rb 2 KSiF 7 (a = 7.88 3 ; c = 5.72 4 A), all colourless, Rb 3 CrF 7 (a = 8.08 4 ; c = 5.90 2 A), Cs 3 CrF 7 (a 8.39 0 ; c = 6.24 7 A), both pink, K 3 MnF 7 (a = 11.14 6 ; b = 11.00 5 ; c = 5.63 1 A), Rb 3 MnF 7 (a = 8.05 0 ; c = 5.89 0 A), Cs 3 MnF 7 (a 8.36 9 ; c = 6.23 3 A), each lemon yellow, and Rb 3 NiF 7 (a = 7.97 8 ; c = 5.85 7 A) and Cs 3 NiF 7 (a = 8.30 7 ; c = 6.19 2 A), both bright carmine red. Proposals for structure, due to Guinier-Simon powder datas (Cu-Kα), are based on the assumption that these fluorides (K 3 MnF 7 exception) are isotypic with K 3 SiF 7 , P4/mbm. Calculations of the Madelung Part of Lattice Energy, MAPLE, confirm the adopted parameters of position. Effective Coordination Numbers, ECoN, calculated by use of Mean Fictive Ionic Radii, MEFIR, are calculated and discussed. Raman spectra indicate the presence of octahedral groups [MF 6 ] in case of Rb 3 SiF 7 , and Cs 3 TiF 7 . The magnetic behaviour of A 3 MnF 7 is measured (70-293 K). (author)

  19. Microstructure and wear resistance of laser clad TiC + NiCrBSi composite layers on Ti-6Al-4V alloy%TC4钛合金激光熔覆TiC+M涂层组织和耐磨性能研究

    Institute of Scientific and Technical Information of China (English)

    孙荣禄; 杨贤金

    2006-01-01

    用CO2激光在TC4合金表面熔覆TiC+Ti和TiC+NiCrBSi金属陶瓷涂层,分析了熔覆层的微观组织,测试了熔覆层的干滑动磨损性能.结果表明,在TiC+Ti激光熔覆层中,TiC颗粒全部溶解,熔覆层的组织是在β-Ti基体上分布着TiC树枝晶;在TiC+NiCrBSi激光熔覆层中,TiC颗粒部分溶解,熔覆层的组织是在γ-Ni树枝晶和γ-Ni+M23(CB)6共晶的基体上分布着细小的TiC颗粒和TiC树枝晶.TiC+Ti激光熔覆层的显微硬度在500~700HV之间,质量磨损率约为TC4合金的1/3;TiC+NiCrBSi激光熔覆层的显微硬度在900~1100HV之间,质量磨损率约为TC4合金的1/10.

  20. properties of Cr(C,N) hard coatings deposited in Ar-C2H2-N2 plasma

    International Nuclear Information System (INIS)

    Macek, M.; Cekada, M.; Kek, D.; Panjan, P.

    2002-01-01

    Mechanical properties, microstructure and the average chemical composition of Cr(C,N) hard coatings deposited in Ar-C 2 H 2 -N 2 plasma strongly depends on the partial pressure of the reactive gases (N 2 , C 2 H 2 ) and on the type of the deposition equipment. In this study we report on the properties of Cr(C,N) hard coatings deposited by means of the triode ion plating in the BAI 730 apparatus and those prepared by sputter deposition in Balzers Sputron in the pressure range from 0.12 Pa (pure Ar) up to 0.35 Pa with different ratios (0-100%) between C 2 H 2 and N 2 . At first mechanical properties (microhardness and adhesion) of coatings were analyzed on the common way. Internal stress was measured by the radius of substrate curvature. Chemical composition of coatings was analyzed by means of AES while the Raman and XPS spectroscopy was used to determined the nature of carbon bonding in the Cr(C,N) films. Microstructure was determined by XRD as well as by means of TEM and TED. Chemical state of various elements in the coating has been studied by XPS. The ratio of the carbide bond (C-Cr) against the C-C and C-H bonds was calculated. The existence of the graphite phase in some Cr(C,N) coatings was confirmed by Raman spectroscopy. (Authors)

  1. Hexagonal perovskites with cationic vacancies. 1. Compounds of the type Ba/sub 2/Bsub(1/3)sup(III) vacantsub(2/3) Resup(VII)O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Jooss, I [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-04-01

    Compounds of type Ba/sub 2/Bsub(1/3)sup(III)vacantsub(2/3)Resup(VII)O/sub 6/ are formed with Bsup(III) = Sm-Gd, Ho-Lu, Y, Sc, In (yellow); Tb (black-brown); Dy (yellow-orange). They crystallize with Bsup(III) = Sm-Lu, Y and Sc in a rhombohedral layer structure of 12 L-type (space group R3m; sequence: cchhcchhcchh) with 6 formula units in the unit cell.

  2. High reflectance Cr/C multilayer at 250 eV for soft X-ray polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Mingwu; Jiang, Li; Zhang, Zhong; Huang, Qiushi [MOE Key Laboratory of Advanced Micro-Structured Materials, Institute of Precision Optical Engineering (IPOE), School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Wang, Zhanshan, E-mail: wangzs@tongji.edu.cn [MOE Key Laboratory of Advanced Micro-Structured Materials, Institute of Precision Optical Engineering (IPOE), School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); She, Rui; Feng, Hua [Department of Engineering Physics, Tsinghua University, Beijing (China); Wang, Hongchang [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2015-10-01

    X-ray reflection near 45° via multilayer mirrors can be used for astronomical polarization measurements. A Cr/C multilayer mirror (designed for X-ray polarimetry at 250 eV), with a period thickness of 3.86 nm and a bi-layer number of 100, was fabricated using direct current magnetron sputtering. Grazing incidence X-ray reflectometry at 8 keV and transmission electron microscopy were used to investigate the multilayer structure. Different models were introduced to fit the hard X-ray reflectivity curve, which indicates that the layer thickness of two materials slightly drifts from the bottom to the top of the stack. Both the chromium and carbon layers are amorphous with asymmetric interfaces, while the Cr-on-C interface is slightly wider. Based on the good quality of the multilayer structure, a high reflectivity of 21.8% for the s-polarized light was obtained at 250 eV at a grazing incidence angle of 40.7°. The fabricated Cr/C multilayer mirror exhibits high reflectivity and polarization levels in the energy region of 240 eV–260 eV. - Highlights: • We fabricated Cr/C multilayer with 3.8 nm d-spacing. • X-ray reflectometry was used to determine the exact structure of Cr/C multilayer. • A high reflectivity of 21.8% for the s-polarized light was obtained at 250 eV. • Both Cr and C were found to be amorphous with slightly asymmetric interfaces. • A 4-layer model was used to fit and explain the results.

  3. Half-metallic antiferromagnetism in double perovskite BiPbCrCuO6

    International Nuclear Information System (INIS)

    Weng, Ke-Chuan; Wang, Y. K.

    2015-01-01

    The electronic structure and magnetic properties of BiPbCrCuO 6 double perovskite are investigated based on first-principles density functional calculations with generalized gradient approximation (GGA) and GGA incorporated with Coulomb correlation interaction U (GGA + U). The results suggest the half-metallic (HM) and antiferromagnetic (AFM) properties of BiPbCrCuO 6 double perovskite. The HM-AFM property of the double perovskite is caused by the double-exchange mechanism between neighboring Cr 5+ (t 2g 1 ↓) and Cu 2+ (t 2g 3 ↑t 2g 3 ↓e g 2 ↑e g ↓) via the intermediate O 2− (2s 2 2p 6 ) ion

  4. Amorphization of C-implanted Fe(Cr) alloys

    International Nuclear Information System (INIS)

    Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

    1991-01-01

    The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

  5. Highly (002) textured large grain bcc Cr{sub 80}Mn{sub 20} seed layer on Cr{sub 50}Ti{sub 50} amorphous layer for FePt-C granular film

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Seong-Jae, E-mail: jsjigst@ecei.tohoku.ac.jp; Saito, Shin [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Hinata, Shintaro [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Japan Society for the Promotion of Science Research Fellow (PD), 5-3-1, Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Takahashi, Migaku [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2015-05-07

    Effect of bcc Cr{sub 80}Mn{sub 20} seed layer and Cr{sub 50}Ti{sub 50} amorphous texture inducing layer on the heteroepitaxy system in FePt-C granular film was studied by introducing a new concept of the layered structure. The concept suggested that the large grain seed layer in which the crystallographic texture was initially formed on an amorphous layer in the layered structure can reduce the angular distribution of (002) c-axis crystal orientation in the FePt-C granular film owing to heteroepitaxial growth. Structure analysis by X-ray diffraction revealed that (1) when the substrate heating temperature was elevated from 300 °C to 500 °C, grain size in the seed layer increased from 9.8 nm to 11.6 nm, and then decreased with further increasing the substrate temperature. The reduction of the grain size over 500 °C corresponds to the crystallization of the amorphous texture inducing layer, (2) when the grain size increased from 9.8 nm to 11.6 nm, the angular distribution of the (002) orientation in the seed layer dramatically decreased from 13.7° to 4.1°. It was shown that the large grain seed layer increased the perpendicular hysteresis in FePt-C granular film.

  6. Cell- and stage-specific chromatin structure across the Complement receptor 2 (CR2/CD21) promoter coincide with CBF1 and C/EBP-beta binding in B cells.

    Science.gov (United States)

    Cruickshank, Mark N; Fenwick, Emily; Karimi, Mahdad; Abraham, Lawrence J; Ulgiati, Daniela

    2009-08-01

    Stringent developmental transcription requires multiple transcription factor (TF) binding sites, cell-specific expression of signaling molecules, TFs and co-regulators and appropriate chromatin structure. During B-lymphopoiesis, human Complement receptor 2 (CR2/CD21) is detected on immature and mature B cells but not on B cell precursors and plasma cells. We examined cell- and stage-specific human CR2 gene regulation using cell lines modeling B-lymphopoiesis. Chromatin accessibility assays revealed a region between -409 and -262 with enhanced accessibility in mature B cells and pre-B cells, compared to either non-lymphoid or plasma cell-types, however, accessibility near the transcription start site (TSS) was elevated only in CR2-expressing B cells. A correlation between histone acetylation and CR2 expression was observed, while histone H3K4 dimethylation was enriched near the TSS in both CR2-expressing B cells and non-expressing pre-B cells. Candidate sites within the CR2 promoter were identified which could regulate chromatin, including a matrix attachment region associated with CDP, SATB1/BRIGHT and CEBP-beta sites as well as two CBF1 sites. ChIP assays verified that both CBF1 and C/EBP-beta bind the CR2 promoter in B cells raising the possibility that these factors facilitate or respond to alterations in chromatin structure to control the timing and/or level of CR2 transcription.

  7. Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

    OpenAIRE

    Wen-Tao Yu; Jing Li; Cheng-Bin Shi; Qin-Tian Zhu

    2016-01-01

    The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix duri...

  8. Synthesis of polysubstituted 4,5,6,7-tetrahydrofuro[2,3-c]pyridines by a novel multicomponent reaction.

    Science.gov (United States)

    Fayol, Aude; Zhu, Jieping

    2004-01-08

    [reaction: see text] A novel three-component synthesis of tetrahydrofuro[2,3-c]pyridines from readily accessible starting materials is described. Simply heating a toluene solution of an aminopentynoate, an aldehyde, and an alpha-isocyanoacetamide in the presence of ammonium chloride provided the 4,5,6,7-tetrahydrofuro[2,3-c]pyridines in good to excellent yield. The fused ring system is produced in this one-pot process by the concomitant formation of five chemical bonds.

  9. A new organically templated gallium(III)-doped chromium(III) fluorophosphite, (C2H10N2)[Ga0.98Cr0.02(HPO3)F3] hydrothermal synthesis, crystal structure and spectroscopic properties

    International Nuclear Information System (INIS)

    Fernandez-Armas, Sergio; Mesa, J.L.; Pizarro, J.L.; Lezama, Luis; Arriortua, M.I.; Rojo, T.

    2004-01-01

    A new organically templated fluoro-phosphite gallium(III)-doped chromium(III) with formula (C 2 H 10 N 2 )[Ga 0.98 Cr 0.02 (HPO 3 )F 3 ] has been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structure has been solved from X-ray single-crystal data. The compound crystallizes in the P2 1 2 1 2 1 orthorhombic space group, with the unit-cell parameters a=12.9417(7) A, b=9.4027(6) A, c=6.3502(4) A and Z=4. The final R factors were R1=0.022 (all data) and wR2=0.050. The crystal structure consists of [Ga 0.98 Cr 0.02 (HPO 3 )F 3 ] 2- anionic chains extended along the c-axis, with the ethylenediammonium cations placed in the cavities of the structure delimited by three different chains. The IR and Raman spectra show the characteristic bands of the phosphite oxoanion. The diffuse reflectance spectroscopy allowed us to calculate the Dq and Racah parameters of the Cr(III) cations in octahedral environment. The values are Dq=1375 cm -1 , B=780 cm -1 and C=3420 cm -1 . The polycrystalline ESR spectra performed at X and Q-bands show the signals belonging to the diluted Cr(III) cation in this phase. From the fit of the X-band ESR spectrum at 4.2 K, the calculated values of the axial (D) and rhombic (E) distortion parameters are 0.075 and 0.042 cm -1 , respectively, the components of the g-tensor being g x =1.98, g y =1.99 and g z =1.90

  10. Substitution of indium for chromium in TlIn5−xCrxSe8: crystal structure of TlIn4.811(5Cr0.189(5Se8

    Directory of Open Access Journals (Sweden)

    Robin Lefèvre

    2017-04-01

    Full Text Available The new thallium penta(indium/chromium octaselenide, TlIn4.811(5Cr0.189(5Se8, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn5Se8 in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a. In the crystal structure, edge-sharing InSe6 octahedra, and (In,CrSe6 octahedra and InSe4 tetrahedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

  11. An ab initio study on the structural, electronic and mechanical properties of quaternary full-Heusler alloys FeMnCrSn and FeMnCrSb

    Science.gov (United States)

    Erkişi, Aytaç

    2018-06-01

    The quaternary full Heusler alloys FeMnCrSn and FeMnCrSb, which have face-centred cubic (FCC) crystal structure and conform to ? space group with 216 space number, have been investigated using Generalised Gradient Approximation (GGA) in the Density Functional Theory (DFT) as implemented in VASP (Vienna Ab initio Simulation Package) software. These alloys are considered in ferromagnetic (FM) order. After the investigation of structural stability of these alloys, their mechanical and thermal properties and also electronic band structures have been examined. The calculated spin-polarised electronic band structures and total electronic density of states (DOS) within GGA approximation show that these alloys can exhibit both metallic and half-metallic characters in different structural phases. The calculated formation enthalpies and the plotted energy-volume graphs show that Type-III phase is most stable structural phase for these materials. Also, FeMnCrSb alloy in Type-I/Type-III phases and FeMnCrSn alloy in Type-III phase show half-metallic behaviour with integer total magnetic moments almost 2 and 1 μB per formula unit, respectively, since there are band gaps observed in spin-down states, whereas they have metallic behaviour in majority bands. Other structural phases of both systems are also metallic. Moreover, the calculated elastic constants and the estimated anisotropy shear factors indicate that these materials are stable mechanically in all of three phases except FeMnCrSn in Type-I phase that does not satisfy Born stability criteria in this phase and have high anisotropic behaviour.

  12. The cartilage-derived, C-type lectin (CLECSF1): structure of the gene and chromosomal location.

    Science.gov (United States)

    Neame, P J; Tapp, H; Grimm, D R

    1999-09-03

    Cartilage is a tissue that is primarily extracellular matrix, the bulk of which consists of proteoglycan aggregates constrained within a collagen framework. Candidate components that organize the extracellular assembly of the matrix consist of collagens, proteoglycans and multimeric glycoproteins. We describe the human gene structure of a potential organizing factor, a cartilage-derived member of the C-type lectin superfamily (CLECSF1; C-type lectin superfamily) related to the serum protein, tetranectin. We show by Northern analysis that this protein is restricted to cartilage and locate the gene on chromosome 16q23. We have characterized 10.9 kb of sequence upstream of the first exon. Similarly to human tetranectin, there are three exons. The residues that are conserved between CLECSF1 and tetranectin suggest that the cartilage-derived protein forms a trimeric structure similar to that of tetranectin, with three N-terminal alpha-helical domains aggregating through hydrophobic faces. The globular, C-terminal domain that has been shown to bind carbohydrate in some members of the family and plasminogen in tetranectin, is likely to have a similar overall structure to that of tetranectin.

  13. Structure and phase transitions of the 6,6-cyclopropane isomer of C61H2

    International Nuclear Information System (INIS)

    Stetzer, M.R.; Heiney, P.A.; Stephens, P.W.; Dinnebier, R.E.; Zhu, Q.; McGhie, A.R.; Strongin, R.M.; Brandt, B.M.; Smith, A.B. III

    2000-01-01

    We have used x-ray powder diffraction and differential scanning calorimetry to study the crystalline structures and thermal behavior of the 6,6-cyclopropane isomer of C 61 H 2 . At room temperature, the C 61 H 2 cyclopropane molecules, like those of the 6,5-annulene isomer and C 60 O epoxide, are orientationally disordered and crystallize on a face-centered-cubic lattice such that their methylene groups are statistically disordered among the octahedral voids. Unlike 6,5-C 61 H 2 and C 60 O, the low-temperature structure is not Pa3-bar, but rather a low-symmetry orthorhombic lattice in which a≅b< c. The orientational melting takes place via a two-step transition centered around 198-213 K

  14. Phase-field simulation of nucleation and growth of M{sub 23}C{sub 6} carbide and ferromagnetic phases during creep deformation in Type 304 steel

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, Yuhki, E-mail: tsukada@silky.numse.nagoya-u.ac.j [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Atsuhiro; Murata, Yoshinori [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Takaya, Shigeru [Japan Atomic Energy Agency, 4002 Narita-cho, O-arai-machi, Higashi-ibaraki-gun, Ibaraki 311-1393 (Japan); Koyama, Toshiyuki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Morinaga, Masahiko [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2010-06-15

    A phase-field method was applied to the simulation of simultaneous nucleation and growth of both M{sub 23}C{sub 6} carbide and ferromagnetic {alpha} phases during the creep process in Type 304 steel. Nucleation events of these product phases were explicitly introduced through a probabilistic Poisson seeding process based on local nucleation rates that were calculated as a function of local concentration. The defect energy of the creep dislocations near the carbides, which increases during creep, was integrated into the nucleation driving force for the {alpha} phase. The simulation used in this study accurately reproduced changes in the amounts of the precipitated phases as a function of creep time. Furthermore, we examine the effect of the dislocation density on precipitation of the {alpha} phase, and show that the phase-field method is useful for examining the stochastic and kinetic phenomenon of phase transformation.

  15. Cytochrome c6B of Synechococcus sp. WH 8102 – Crystal structure and basic properties of novel c6-like family representative

    International Nuclear Information System (INIS)

    Zatwarnicki, Pawel; Barciszewski, Jakub; Krzywda, Szymon; Jaskolski, Mariusz; Kolesinski, Piotr; Szczepaniak, Andrzej

    2014-01-01

    Highlights: • Crystal structure of cytochrome c 6B from Synechococcus sp. WH 8102 was solved. • Basic biophysical properties of cytochrome c 6B were determined. • Cytochrome c 6B exhibits similar architecture to cytochrome c 6 . • Organization of heme binding pocket of cytochrome c 6B differs from that of c 6 . • Midpoint potential of cytochrome c 6B is significantly lower than of cytochrome c 6 . - Abstract: Cytochromes c are soluble electron carriers of relatively low molecular weight, containing single heme moiety. In cyanobacteria cytochrome c 6 participates in electron transfer from cytochrome b 6 f complex to photosystem I. Recent phylogenetic analysis revealed the existence of a few families of proteins homologous to the previously mentioned. Cytochrome c 6A from Arabidopsis thaliana was identified as a protein responsible for disulfide bond formation in response to intracellular redox state changes and c 550 is well known element of photosystem II. However, function of cytochromes marked as c 6B , c 6C and c M as well as the physiological process in which they take a part still remain unidentified. Here we present the first structural and biophysical analysis of cytochrome from the c 6B family from mesophilic cyanobacteria Synechococcus sp. WH 8102. Purified protein was crystallized and its structure was refined at 1.4 Å resolution. Overall architecture of this polypeptide resembles typical I-class cytochromes c. The main features, that distinguish described protein from cytochrome c 6 , are slightly red-shifted α band of UV–Vis spectrum as well as relatively low midpoint potential (113.2 ± 2.2 mV). Although, physiological function of cytochrome c 6B has yet to be determined its properties probably exclude the participation of this protein in electron trafficking between b 6 f complex and photosystem I

  16. 23 CFR 1335.6 - Strategic plan.

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Strategic plan. 1335.6 Section 1335.6 Highways NATIONAL... § 1335.6 Strategic plan. A strategic plan shall— (a) Be a multi-year plan that identifies and prioritizes... performance-based measures by which progress toward those goals will be determined; and (c) Be submitted to...

  17. High-pressure structural behavior of the double perovskite Sr2CrReO6: an experimental and theoretical study

    DEFF Research Database (Denmark)

    Olsen, J.S.; Gerward, Leif; Vaitheeswaran, G.

    2009-01-01

    The high-pressure structural behavior of Sr2CrReO6 has been studied experimentally using synchrotron radiation and the diamond anvil cell and theoretically using density functional theory. The experimental zero-pressure bulk modulus is B0=1704GPa and the pressure derivative is B0'=4.71.0. These r...

  18. Morphology, Structure and Nonstoichiometry of ZnCr2O4 Nanophased Powder

    Directory of Open Access Journals (Sweden)

    O. Milosevic

    2003-10-01

    Full Text Available It is well established that gas/humidity-sensing properties of spinels are markedly influenced by their stoichiometry and microstructure. In this work nucleation and spinel phase development in the Zn-Cr-O system were investigated from the viewpoint of structural and morphological phenomena occurred during nanophased particle synthesis through aerosol reaction. The aerosol was generated from nitrates precursor solution using ultrasonic atomizer operated at 1.7 MHz. The influence of different decomposition schedules on the particle chemical content and morphology was determined by adjusting the processing parameters (aerosol droplet density 3.9x106 droplets/cm3, droplet velocity 0.035m/s, max. temperature 900oC and residence times 3, 6 and 9s. A composite particle structure comprised of primary crystallites sized from 22 to 44nm is revealed by SEM and TEM analysis. XRD structural analysis (crystallite size, microstrains, unit cell and ionic occupancies is performed in accordance with procedure based on Koalariet-Xfit program. A certain degree of non-stochiometry is characteristic for all powders. Homogenous distribution of the constituting elements and Zn/Cr ratio of about 0.68 are proved by EDAX mapping analysis in 470nm sized as-prepared particles. After additional treatment at 1000oC octahedral crystals form with the (111 surface dominat. Evaluated spinel non-stochiometry (Zn/Cr=0.58 is a result of the ZnO dissolving (1.9%wt in the stoichiometric ZnCr2O4. Determination of the way by which the ZnO is incorporated into the spinel lattice is performed according to the procedure based on calculation of both formation and attachment energies.

  19. Effects of Aging and W Addition on the Microstructure of Fe-Cr-Mn-N Stainless Steels

    International Nuclear Information System (INIS)

    Jeon, Yu Taek; Joo, Uk Hyon; Park, Yong Soo; Kim, Young Sik

    2000-01-01

    The effects of aging treatment on the precipitation behaviors of Fe-Cr-Mn-N stainless steels were studied using a transmission electron microscopy, scanning electron microscopy, optical microscopy and XRD. In the austenitic stainless steel having a single phase. M23C6 carbides were first precipitated in the grain boundary by aging and then grew from grain boundary into grain with aging time. Carbides showed lamellar structures. It was shown from the analysis of spot patterns that carbides had a coherent relation with matrix and their lattice parameter was roughly three times that of austenite. During initial stages of M23C6 carbide precipitation, the iron content was quite high. With increasing aging time, the chromium content was increased. As the tungsten was added to improve the corrosion resistance of the Fe-Cr-Mn-N stainless steels, ferrite phase was formed. This ferrite phase was decomposed to chi(χ) phase and secondary austenite. Chi phase was mainly enriched with tungsten, chromium and tungsten were depleted in the secondary austenite due to the formation of chi phase. M23C6 carbides were also formed in the grain boundary. Nickel stabilized the austenite phase and decreased the ferrite volume fraction. But nickel content was not sufficient to suppress the formation of ferrite, and precipitation behaviors were not changed

  20. Effects of aging treatment and W addition on the microstructure of Fe-Cr-Mn stainless steels

    International Nuclear Information System (INIS)

    Jeoun, Y. T.; Zoo, W. H.; Kim, Y. S.; Park, Y. S.

    1999-01-01

    The effects of aging treatment on the precipitaion behaviors of Fe-Cr-Mn-W stainless steels were studied using a transmission electron microscopy, scanning electron microscopy, optical microscopy and XRD. In the austenitic stainless steel showing a single phase, M 23 C 6 carbides were first precipitated in the grain boundary by aging and then grew from grain boundary into grain with aging time. Carbides showed lamellar structures. It was shown from the analysis of spot patterns that carbides had a coherent relation with matrix and their lattice parameter was roughly three times that of austenite. During initial stages of M 23 C 6 carbide precipitaion, the iron content was quite high. With increasing aging time, the chromium content increased. As the tungsten was added to improve the corrosion resistance of the Fe-Cr-Mn stainless steels, ferrite phase was formed. These ferrite phase was decomposed to chi(χ) phase and secondary austenite. Chi phase was mainly enriched with tungsten, chromium and tungsten were depleted in the secondary austenite due to the formation of chi phase. M 23 C 6 carbides were also formed in the grain boundary. Nickel stabilized the austenite phase and decreased the ferrite volume fraction. But nickel content was not sufficient to suppress the formation of ferrite, and precipitaion behaviors were not changed

  1. Creep damage behaviour of modified 9Cr-1Mo steel weld joints

    International Nuclear Information System (INIS)

    Sakthivel, T.; Laha, K.; Vasudevan, M.; Panneer Selvi, S.

    2016-01-01

    Creep deformation and rupture behaviour of modified 9Cr-1Mo steel weld joints fabricated by single-pass activated TIG (A-TIG) and shielded metal arc welding (SMAW) processes have been investigated at 923 K over a stress range of 50 to 110 MPa after post weld heat treatment (PWHT). The weld joints exhibited significantly lower creep rupture lives than the base metal at lower applied stresses. Creep rupture location of the weld joints were found to occur in the ICHAZ. An extensive localized creep deformation, coarsening of M 23 C 6 precipitates in the ICHAZ with creep exposure led to the premature type IV failure of the joints. The coarsening of M 23 C 6 precipitates was extensive in the mid-section of the ICHAZ than the sub-surface of the joints, and was more predominant in the SMAW joint. While A-TIG weld joint exhibited reduced creep cavitation and coarsening of M 23 C 6 precipitates due to lower deformation constraints by adjacent regions in the ICHAZ. Hence, A-TIG weld joint exhibited higher creep rupture life than the SMAW joint. (author)

  2. The Development of the Low-Cost Titanium Alloy Containing Cr and Mn Alloying Elements

    Science.gov (United States)

    Zhu, Kailiang; Gui, Na; Jiang, Tao; Zhu, Ming; Lu, Xionggang; Zhang, Jieyu; Li, Chonghe

    2014-04-01

    The α + β-type Ti-4.5Al-6.9Cr-2.3Mn alloy has been theoretically designed on the basis of assessment of the Ti-Al-Cr-Mn thermodynamic system and the relationship between the molybdenum equivalent and mechanical properties of titanium alloys. The alloy is successfully prepared by the split water-cooled copper crucible, and its microstructures and mechanical properties at room temperature are investigated using the OM, SEM, and the universal testing machine. The results show that the Ti-4.5Al-6.9Cr-2.3Mn alloy is an α + β-type alloy which is consistent with the expectation, and its fracture strength, yield strength, and elongation reach 1191.3, 928.4 MPa, and 10.7 pct, respectively. Although there is no strong segregation of alloying elements under the condition of as-cast, the segregation of Cr and Mn is obvious at the grain boundary after thermomechanical treatment.

  3. Structural Stability and Electronic Properties of Na2C6O6 for a Rechargeable Sodium-ion Battery

    Science.gov (United States)

    Yamashita, Tomoki; Fujii, Akihiro; Momida, Hiroyoshi; Oguchi, Tamio

    2014-03-01

    Sodium-ion batteries have been explored as a promising alternative to lithium-ion batteries owing to a significant advantage of a natural abundance of sodium. Recently, it has been reported that disodium rhodizonate, Na2C6O6, exhibit good electrochemical properties and cycle performance as a minor-metal free organic cathode for sodium-ion batteries. However, its crystal structures during discharge/charge cycle still remain unclear. In this work, we theoretically propose feasible crystal structures of Na2+xC6O6 using first principles calculations. A structural phase transition has been found: Na4C6O6 has a different C6O6 packing arrangement from Na2C6O6. Electronic structures of Na2+xC6O6 during discharge/charge cycle are also discussed. Our predictions could be the key to understanding the discharge/charge process of Na2C6O6. Supported by MEXT program ``Elements Strategy Initiative to Form Core Rersearch Center'' (since 2012), MEXT; Ministry of Education Culture, Sports, Science and Technology, Japan.

  4. Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure

    International Nuclear Information System (INIS)

    Eliziario Nunes, Sayonara; Wang, Chun-Hai; So, Karwei; Evans, John S.O.; Evans, Ivana Radosavljević

    2015-01-01

    We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn 2 VO 6 , known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn 2 VO 6 adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO 4 tetrahedra, ZnO 6 octahedra and VO 4 tetrahedra, and Bi 2 O 12 dimers. It is the only known member of the BiM 2 AO 6 (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family which does not appear to be structurally closely related to others. The electronic structure of BiZn 2 VO 6 , calculated by DFT methods, shows that it is an indirect gap semiconductor with a calculated band gap of 1.6 eV, which compares favourably to the experimentally measured value of 2.4 eV. - Graphical abstract: The crystal structure of BiZn 2 VO 6 , a new structure type in the BiM 2 AO 6 (M=Mg, Ca, Cd, Cu, Pb, Mn, Zn; A=V, P, As) family. - Highlights: • Structure solution from PXRD data by repeated minimisations from random starting values. • New structure type in the BiM 2 AO 6 (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family. • Electronic structure calculation

  5. Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=–F, –Cl, –Br, –CH3, –C6H4, –F2, –(CH3)2) materials

    International Nuclear Information System (INIS)

    Buragohain, Amlan; Couck, Sarah; Van Der Voort, Pascal; Denayer, Joeri F.M.; Biswas, Shyam

    2016-01-01

    Four existing and three new functionalized chromium terephthalates having MIL-101 topology and denoted as Cr-MIL-101-X (existing ones with X=–F, 1-F; –Cl, 2-Cl; –Br, 3-Br; –CH 3 , 4-CH 3 ; new ones with X=–C 6 H 4 , 5-C 6 H 4 ; –F 2 , 6-F 2 , –(CH 3 ) 2 , 7-(CH 3 ) 2 ) were synthesized under hydrothermal conditions. All the materials except 5-C 6 H 4 could be prepared by a general synthetic route, in which the mixtures of CrO 3 , H 2 BDC-X (BDC=1,4-benzenedicarboxylate) linkers, conc. HCl and water with a molar ratio of 1:1:3.9:222.2 were reacted at 180 °C for 144 h. Compared to the 144 h of synthesis time, three of the compounds, namely 1-Cl, 2-Br and 5-C 6 H 4 , could be prepared in much shorter reaction times (12–18 h at 180–210 °C). The materials possess high thermal stability up to 270–300 °C in an air atmosphere. The activated compounds exhibit significant porosity (S BET range: 1273–2135 m 2 g −1 ). At 0 °C and 1 bar, the CO 2 adsorption capacities of the compounds fall in the 1.7–2.9 mmol g −1 range. Compounds 1-F and 6-F 2 showed enhanced CO 2 uptake values compared to parent Cr-MIL-101. The benzene adsorption capacities of the compounds lie in the range of 66.2–139.5 molecules per unit cell at 50 °C and p/p 0 =0.35. The increased benzene uptake value of 1-F compared to un-functionalized Cr-MIL-101 and 4-CH 3 suggests that the fluorination has induced more hydrophobicity in Cr-MIL-101 as compared to the methylation. - Graphical abstract: Benzene adsorption by seven functionalized Cr-MIL-101-X metal-organic framework (MOF) materials Display Omitted - Highlights: • Seven functionalized Cr-MIL-101-X materials were synthesized solvothermally. • All Cr-MIL-101-X materials exhibited high thermal stability up to 270–300 °C in air. • All Cr-MIL-101-X compounds displayed considerable porosity towards N 2 , CO 2 and benzene. • Mono- and di-fluorinated Cr-MIL-101 materials showed enhanced CO 2 adsorption capacities.

  6. Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao [Rutgers Univ., Piscataway, NJ (United States). Department of Chemistry and Chemical Biology; Dong, Xinglong [King Abdullah University of Science and Technology, Thuwal (Saudi Arabia). Advanced Membranes and Porous Materials Center, Physical Sciences and Engineering Division; Lin, Junzhong [Peking University, Beijing (China). College of Chemistry and Molecular Engineering; Teat, Simon J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Jensen, Stephanie [Wake Forest University, Winston-Salem, NC (United States). Department of Physics; Cure, Jeremy [Univ. of Texas-Dallas, Richardson, TX (United States). Department of Materials Science & Engineering; Alexandrov, Eugeny V. [Samara University (Russia). Samara Center for Theoretical Materials Science (SCTMS; Xia, Qibin [Rutgers Univ., Piscataway, NJ (United States). Department of Chemistry and Chemical Biology; South China University of Technology, Guangzhou (China). School of Chemistry and Chemical Engineering; Tan, Kui [Univ. of Texas-Dallas, Richardson, TX (United States). Department of Materials Science & Engineering; Wang, Qining [Rutgers Univ., Piscataway, NJ (United States). Department of Chemistry and Chemical Biology; Olson, David H. [Rutgers Univ., Piscataway, NJ (United States). Department of Chemistry and Chemical Biology; Proserpio, Davide M. [Samara University (Russia). Samara Center for Theoretical Materials Science (SCTMS; Università degli Studi di Milano, Milano (Italy). Dipartimento di Chimica; Chabal, Yves J. [Univ. of Texas-Dallas, Richardson, TX (United States). Department of Materials Science & Engineering; Thonhauser, Timo [Wake Forest University, Winston-Salem, NC (United States). Department of Physics; Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Department of Chemistry; Sun, Junliang [Peking University, Beijing (China). College of Chemistry and Molecular Engineering; Han, Yu [King Abdullah University of Science and Technology, Thuwal (Saudi Arabia). Advanced Membranes and Porous Materials Center, Physical Sciences and Engineering Division; Li, Jing [Rutgers Univ., Piscataway, NJ (United States). Department of Chemistry and Chemical Biology

    2018-05-01

    As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr6O4(OH)4(bptc)3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr6O4(OH)8(H2O)4(abtc)2, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.

  7. Radiolabeling and animal experimental studies of anti-breast cancer McAb 6C6 and mouse-human chimeric antibody 6C6CHI

    International Nuclear Information System (INIS)

    Yang Zhi; Hu Xiaoqian; Li Erqiu

    2003-01-01

    The aim of this work is to study bio-distribution and tumor absorption of anti breast cancer monoclonal antibody 6C6 and its chimeric antibody 6C6-CHI. The modified Schwartz method was employed to label 6C6 and 6C6CHI with 99 Tc m . The labeled antibody was injected to mouse via tail vein and the blood clearance and whole body clearance were observed. Nude mice bearing breast cancer MCF7 were injected with 99 Tc m -labeled antibody and the bio-distribution was studied and imaged with γ-ray camera. The yield of the two labeled antibodies was more than 90% and their immunoactivities were more than 80%. The whole body eliminated half-time of 99 Tc m -6C6 was 4.1h, and the half-times in blood were T α =0.55h and T β =12.42h respectively. The whole body half-time of 99 Tc m -6C6CHI was 4.28h and the half-times in blood were T α =0.98h and T β =12.42h respectively. The bio-distribution of nude mice bearing breast cancer MCF7 cells was as follows: the ID%/g of tumor and blood was (7.42±0.85) and (5.67±1.44) respectively at 23h after injection of 99 Tc m -6C6. The T/NT (tumor to non tumor) ratios were all more than 1.0 except kidney and the ID%/g of tumor and blood was (4.23±0.64) and (6.97±0.23) respectively at 23 h after injection of 99 Tc m -6C6CHI. The T/NT (tumor to non tumor) ratios were all more than 1.0 except blood and kidney. The γ imaging results showed that the tumor was imaged clearly at 24h after injection of radiolabeled antibodies and the other organs did not concentrate the antibodies except kidney. Anti-breast cancer monoclonal antibody 6C6 can be well located in tumor. Although ID%/g of tumor of the chimeric antibody 6C6CHI was slightly lower than that of 6C6 antibody, and ID%/g of blood was higher than that of 6C6, the tumor imaging of 6C6-CHI was also clear

  8. Structural, magnetic, and dielectric properties of multiferroic Co{sub 1−x}Mg{sub x}Cr{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kamran, M.; Ullah, A. [Nanomagnetism and Nanotechnology Laboratory, International Islamic University, Islamabad 44000 (Pakistan); Rahman, S. [Department of Material Science and Engineering, University of Science and Technology of China Hefei, Anhui 230026 (China); Tahir, A. [Department of Physics, Quaid-e-Azam University, Islamabad 44000 (Pakistan); Nadeem, K., E-mail: kashif.nadeem@iiu.edu.pk [Nanomagnetism and Nanotechnology Laboratory, International Islamic University, Islamabad 44000 (Pakistan); Beijing National Laboratory for Condensed Matter Physics, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Anis ur Rehman, M. [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan); Hussain, S. [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2017-07-01

    Highlights: • Properties of multiferroic Co{sub 1−x}Mg{sub x}Cr{sub 2}O{sub 4} nanoparticles have been studied. • XRD showed that CoCr{sub 2}O{sub 4} and MgCr{sub 2}O{sub 4} are cubic normal spinel structure. • Rietveld refinement of XRD showed no impurity phases. • T{sub c} and T{sub s} showed decreasing trend with increasing Mg concentration. • Dielectric properties were improved for x = 0.6 Mg concentration. - Abstract: We examined the structural, magnetic, and dielectric properties of Co{sub 1−x}Mg{sub x}Cr{sub 2}O{sub 4} nanoparticles with composition x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1 in detail. X-ray diffraction (XRD) revealed normal spinel structure for all the samples. Rietveld refinement fitting results of the XRD showed no impurity phases which signifies the formation of single phase Co{sub 1−x}Mg{sub x}Cr{sub 2}O{sub 4} nanoparticles. The average crystallite size showed a peak behaviour with maxima at x = 0.6. Raman and Fourier transform infrared (FTIR) spectroscopy also confirmed the formation of single phase normal spinel for all the samples and exhibited dominant vibrational changes for x ≥ 0.6. For x = 0 (CoCr{sub 2}O{sub 4}), zero field cooled/field cooled (ZFC/FC) magnetization curves showed paramagnetic (PM) to ferrimagnetic (FiM) transition at T{sub c} = 97 K and a conical spiral magnetic order at T{sub s} = 30 K. The end members CoCr{sub 2}O{sub 4} (x = 0) and MgCr{sub 2}O{sub 4} (x = 1) are FiM and antiferromagnetic (AFM), respectively. T{sub c} and T{sub s} showed decreasing trend with increasing x, followed by an additional AFM transition at T{sub N} = 15 K for x = 0.6. The system finally stabilized and changed to highly frustrated AFM structure at x = 1 due to formation of pure MgCr{sub 2}O{sub 4}. High field FC curves (5T) depicted nearly no effect on spiral magnetic state, which is attributed to strong exchange B-B magnetic interactions at low temperatures. Dielectric parameters showed a non-monotonous behaviour with

  9. Effect of welding thermal cycles on the structure and properties of simulated heat-affected zone areas in X10CrMoVNb9-1 (T91) steel at a state after 100,000 h of operation

    Energy Technology Data Exchange (ETDEWEB)

    Łomozik, Mirosław, E-mail: miroslaw.lomozik@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland); Hernas, Adam, E-mail: adam.hernas@polsl.pl [Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, 40-019 Katowice, Krasińskiego 8 str. (Poland); Zeman, Marian L., E-mail: marian.zeman@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland)

    2015-06-18

    The article presents results of structural tests (light, scanning electron and scanning transmission electron microscopy) of X10CrMoVNb9-1 (T91) creep-resisting steel after approximately 100,000 h of operation. It was ascertained that the parent metal of T91 steel is characterized by the microstructure of tempered martensite with M{sub 23}C{sub 6} carbide precipitates and few dispersive precipitates of MX-type niobium and vanadium carbonitrides. The most inconvenient change in T91 steel precipitate morphology due to long-term operation is the appearance of the Laves Fe{sub 2}Mo phase which along with M{sub 23}C{sub 6} carbide particles forms elongated blocks and conglomerates on grain boundaries. The article also presents results of tests related to the effect of simulated welding thermal cycles on selected properties of X10CrMoVNb9-1 (T91) grade steel at a state after approximately 100,000 h of operation. The tests involved the determination of the chemical composition of the steel tested as well as impact tests, hardness measurements and microscopic metallographic examination (based on light microscopy) of simulated heat-affected zone (HAZ) areas for a cooling time (t{sub 8/5}) restricted within a range between 3 s and 120 s, with and without heat treatment. The tests revealed that, among other results, hardness values of simulated HAZ areas in X10CrMoVNb9-1 (T91) steel do not guarantee cold crack safety of the steel at the state without additional heat treatment. It was also observed that simulated welding thermal cycles of cooling times t{sub 8/5}=3, 12, 60 and 120 s do not significantly affect the toughness and hardness of simulated HAZ areas of the steel tested.

  10. Stopped-Flow Spectrophotometric Study of the Kinetics and Mechanism of CO2 Uptake by cis-[Cr(C2O4(BaraNH2(OH22]+ Cation and the Acid-Catalyzed Decomposition of cis-[Cr(C2O4(BaraNH2OCO2]− Anion in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Lech Chmurzyński

    2011-09-01

    Full Text Available The kinetics of CO2 uptake by the cis-[Cr(C2O4(BaraNH2(OH22]+ complex cation and the acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− complex anion (where BaraNH2 denotes methyl 3-amino-2,3-dideoxy-b-D-arabino-hexopyranoside were studied using the stopped-flow technique. The reactions under study were investigated in aqueous solution in the 288–308 K temperature range. In the case of the reaction between CO2 and cis-[Cr(C2O4(BaraNH2(OH22]+ cation variable pH values (6.82–8.91 and the constant ionic strength of solution (H+, Na+, ClO4− = 1.0 were used. Carbon dioxide was generated by the reaction between sodium pyruvate and hydrogen peroxide. The acid hydrolysis of cis-[Cr(C2O4(BaraNH2OCO2]− was investigated for varying concentrations of H+ ions (0.01–2.7 M. The obtained results enabled the determination of the number of steps of the studied reactions. Based on the kinetic equations, rate constants were determined for each step. Finally, mechanisms for both reactions were proposed and discussed. Based on the obtained results it was concluded that the carboxylation (CO2 uptake reactions of cis-[Cr(C2O4(BaraNH2(OH22]+ and the decarboxylation (acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− are the opposite of each other.

  11. (E-3-Methyl-6-(3-oxo-3-(thiophen-2-yl-1-propenyl-2(3H-benzothiazolone

    Directory of Open Access Journals (Sweden)

    Yordanka Ivanova

    2016-04-01

    Full Text Available The title compound, (E-3-methyl-6-(3-oxo-3-(thiophen-2-yl-1-propenyl-2(3H-benzothiazolone, was synthesized by Claisen-Schmidt condensation of 3-methyl-2(3H-benzothiazolone-6-carbaldehyde with 2-acetylthiophene in 94% yield. The structure of the target compound was confirmed using 1H-NMR, 13C-NMR, IR, MS, and elemental analysis.

  12. Transmission type Sc/Cr multilayers as a quarter-wave plate for 398.6 eV

    International Nuclear Information System (INIS)

    Kimura, H.; Hirono, T.; Tamenori, Y.; Saitoh, Y.; Salashchenko, N.N.; Ishikawa, T.

    2004-01-01

    Full text: Full polarization measurement using a phase shifter and a polarizer is needed to determine the degree of circular polarization. A quarter-wave plate, which is a phase shifter having retardation of 90 deg., is especially desired for accurate determination of the full polarization measurement for highly circularly polarized light. In the soft x-ray region, a self-standing multilayer with high reflectance can be used as a phase shifter having large retardation angle under transmission geometry. In this region, Mo/Si multilayer has been reported as a quarter-wave plate for photon energy of 97 eV. To perform the full polarization measurement in higher photon energy, we newly developed a quarter-wave plate by transmission type Sc/Cr multilayer. Polarization characteristics of the multilayer were measured by mean of rotating analyzer ellipsometry method using a linearly polarized SR of 398.6 eV. Figure 1 shows the retardation of the multilayer (Sc/Cr, d = 3.15 nm, 300 pairs). As is shown the phase shifter can be used as a quarter-wave plate at the incident angle of 59.7 deg. At this angle its transmittance for p-component and the ratio of those for p- and s-component were 0.4 % and 1.47, respectively

  13. Hot Corrosion Behavior of Bare, Cr3C2-(NiCr) and Cr3C2-(NiCr) + 0.2wt.%Zr Coated SuperNi 718 at 900 °C

    Science.gov (United States)

    Mudgal, Deepa; Singh, Surendra; Prakash, Satya

    2015-01-01

    Corrosion in incinerators, power plants, and chemical industries are frequently encountered due to the presence of salts containing sodium, sulphur, and chlorine. To obviate this problem, bare and coated alloys were tested under environments simulating the conditions present inside incinerators and power plants. 0.2 wt.% zirconium powder was incorporated in the Cr3C2-(NiCr) coating powder. The original powder and Zr containing powder was sprayed on Superni 718 alloy by D-gun technique. The bare and coated alloys were tested under Na2SO4 + K2SO4 + NaCl + KCl and Na2SO4 + NaCl environment. The corrosion rate of specimens was monitored using weight change measurements. Characterization of the corrosion products has been done using FE-SEM/EDS and XRD techniques. Bare and coated alloys showed very good corrosion resistance under given molten salt environments. Addition of 0.2wt.%Zr in Cr3C2-25%(NiCr) coating further greatly reduced the oxidation rate as well as improved the adherence of oxide scale to the coating surface during the time of corrosion.

  14. Microstructural evolution in modified 9Cr-1Mo ferritic/martensitic steel irradiated with mixed high-energy proton and neutron spectra at low temperatures

    International Nuclear Information System (INIS)

    Sencer, B.H.; Garner, F.A.; Gelles, D.S.; Bond, G.M.; Maloy, S.A.

    2002-01-01

    Modified 9Cr-1Mo ferritic/martensitic steel was exposed at 32-57 deg. C to a mixed proton/neutron particle flux and spectrum at the Los Alamos Neutron Science Center. The microstructure of unirradiated 9Cr-1Mo consists of laths, dislocations and carbides. Examination of electron diffraction patterns obtained from extraction replicas of unirradiated 9Cr-1Mo revealed that the precipitate microstructure was primarily dominated by M 23 C 6 carbides. The post-irradiation microstructure contained black-spot damage in addition to precipitates and dislocations. Examination of electron diffraction patterns revealed diffuse rings from M 23 C 6 carbides, indicating amorphization and/or nanocrystallinity. Crystalline MC carbides were also found. No cavity formation was found although a significant amount of helium and hydrogen generation had been generated. TEM-EDS examination of extraction replicas for carbides from unirradiated and irradiated samples did not show any detectable changes in composition of either M 23 C 6 or MC carbides. There was also no evident change in carbide size. Lattice images of M 23 C 6 carbides revealed an amorphous microstructure following irradiation, but MC carbides were still crystalline

  15. Effects of Mo on microstructure of as-cast 28 wt.% Cr–2.6 wt.% C–(0–10) wt.% Mo irons

    Energy Technology Data Exchange (ETDEWEB)

    Imurai, S. [Department of Physics and Materials Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thanachayanont, C.; Pearce, J.T.H. [National Metal and Materials Technology Center, Pathumthani 12120 (Thailand); Tsuda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Chairuangsri, T., E-mail: tchairuangsri@gmail.com [Department of Industrial Chemistry, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-04-01

    Microstructures of as-cast 28 wt.% Cr–2.6 wt.% C irons containing (0–10) wt.% Mo with the Cr/C ratio of about 10 were studied and related to hardness. The experimental irons were cast into dry sand molds. Microstructural investigation was performed by light microscopy, X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometry. It was found that the iron with about 10 wt.% Mo was eutectic/peritectic, whereas the others with less Mo content were hypoeutectic. The matrix in all irons was austenite, partly transformed to martensite during cooling. Mo addition promoted the formation of M{sub 23}C{sub 6} and M{sub 6}C. At 1 wt.% Mo, multiple eutectic carbides including M{sub 7}C{sub 3}, M{sub 23}C{sub 6} and M{sub 6}C were observed. M{sub 23}C{sub 6} existed as a transition zone between eutectic M{sub 7}C{sub 3} and M{sub 6}C, indicating a carbide transition as M{sub 7}C{sub 3}(M{sub 2.3}C) → M{sub 23}C{sub 6}(M{sub 3.8}C) → M{sub 6}C. At 6 wt.% Mo, multiple eutectic carbides including M{sub 7}C{sub 3} and M{sub 23}C{sub 6} were observed together with fine cellular/lamellar M{sub 6}C aggregates. In the iron with 10 wt.% Mo, only eutectic/peritectic M{sub 23}C{sub 6} and M{sub 6}C were found without M{sub 7}C{sub 3}. Mo distribution to all carbides has been determined to be increased from ca. 0.4 to 0.7 in mass fraction as the Mo content in the irons was increased. On the other hand, Cr distribution to all carbides is quite constant as ca. 0.6 in mass fraction. Mo addition increased Vickers macro-hardness of the irons from 495 up to 674 HV{sub 30}. High Mo content as solid-solution in the matrix and the formation of M{sub 6}C or M{sub 23}C{sub 6} aggregates were the main reasons for hardness increase, indicating potentially improved wear performance of the irons with Mo addition. - Highlights: • Mo promoted the formation of M{sub 23}C{sub 6} and M{sub 6}C in the irons with Cr/C ratio of about 10

  16. Evolution of secondary phases in 0.17C-16Cr-11Mn-0.43N austenitic stainless steel at 800 and 850°C: Thermodynamic modeling of phase equilibria and experimental kinetic studies

    Directory of Open Access Journals (Sweden)

    Čička R.

    2012-01-01

    Full Text Available The precipitation of secondary phases was investigated in the 0.17C-16Cr-11Mn-0.43N austenitic stainless steel during annealing at 800 and 850°C for times between 5 min and 100 h. Light microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and differential thermal analysis were used in experiments. Thermodynamic calculations were done by the ThermoCalc database software package. Cr2N and M23C6 were considered to be stable phases at the annealing temperatures. Cells consisting of alternating Cr2N and austenite lamellae were observed in the steel microstructure after sufficiently long annealing. The metastable chi phase was also found in all the annealed samples. After 100 h of annealing the equilibrium sigma started to precipitate. The thermodynamically predicted M6C was not confirmed experimentally in any of the annealed samples. DTA analysis showed the initial precipitation stage was followed by the phase dissolution. For the investigated steel the computational thermodynamics can be used only for qualitative interpretation of the experimental results as the measured endothermal peaks were found to be shifted of about 50 ÷ 70°C related to the computed results.

  17. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

    International Nuclear Information System (INIS)

    Jin, Y.; O'Connell, A.; Kharel, P.; Lukashev, P.; Staten, B.; Tutic, I.; Valloppilly, S.; Herran, J.; Mitrakumar, M.; Bhusal, B.; Huh, Y.; Yang, K.; Skomski, R.; Sellmyer, D. J.

    2016-01-01

    The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2 1 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T C ) significantly above room temperature. The measured T C for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ B /f.u. and 2.78 μ B /f.u., respectively, which are close to the theoretically predicted value of 3 μ B /f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

  18. Characterisation of cathodic arc evaporated CrTiAlN coatings: Tribological response at room temperature and at 400 °C

    Energy Technology Data Exchange (ETDEWEB)

    Georgiadis, Argyrios; Fuentes, Gonzalo G., E-mail: gfuentes@ain.es; Almandoz, Eluxka; Medrano, Angel; Palacio, José F.; Miguel, Adrián

    2017-04-01

    In this work, cathodic arc evaporation CrTiAlN coatings have been deposited on H13 hot work steel and the tribological behavior investigated at room temperature and at 400 °C. The microstructure, composition, roughness, indentation hardness and lattice parameter have been measured as a function of the deposition conditions, mainly given by the different Cr and TiAl vapour fluxes coming from the cathode arrangement in the vacuum reactor. The coating microstructures showed dense, compact columnar growth and a good film adhesion. The lattice parameter measured over the (002) diffraction peaks exhibited a quasi lineal correlation with the Ti/Cr+Al atomic ratio of the samples. In addition, the indentation hardness also increased as the lattice parameter increased. The coefficients of friction unveiled the different tribological behavior of the samples depending on the stoichiomentry and the temperature. At 400 °C, the coefficients of friction showed high dispersion, in contrast to the coherent evolution observed at room temperature. The wear damage at 400 °C was more intense than that observed at room temperature in agreement with the friction evolution observed. The coating with a stoichiometry of Cr{sub 0.23}Ti{sub 0.13}Al{sub 0.22}N{sub 0.42} showed a good wear performance at 400 °C. - Highlights: • CrTiAlN arc coatings deposited on hot work steel using different Cr and TiAl vapour fluxes. • Found correlation between Ti/Cr+Al atomic ratio, hardness and lattice parameters. • COF and wear show coherent evolution and low damage level at room temperature. • COF and wear at 400 °C exhibit higher level of damage than at room temperature. • Cr{sub 0.23}Ti{sub 0.13}Al{sub 0.22}N{sub 0.42} showed a good wear performance at 400 °C.

  19. Pressure Prediction of Electronic, Anisotropic Elastic, Optical, and Thermal Properties of Quaternary (M2/3Ti1/33AlC2 (M = Cr, Mo, and Ti

    Directory of Open Access Journals (Sweden)

    Liang Sun

    2016-01-01

    Full Text Available The electronic, mechanical, anisotropic elastic, optical, and thermal properties of quaternary (M2/3Ti1/33AlC2 (M = Cr, Mo, and Ti under different pressure are systematically investigated by first-principles calculations. The bonding characteristics of these compounds are the mixture of metallic and covalent bonds. With an increase of pressure, the heights of total density of states (TDOS for these compounds decrease at Fermi level. The highest volume compressibility among three compounds is Mo2TiAlC2 for its smallest relative volume decline. The relative bond lengths are decreasing when the pressure increases. The bulk and shear modulus of the one doped with Cr or Mo are larger than those of Ti3AlC2 with pressure increasing. With an increase of pressure, the anisotropy of these compounds also increases. Moreover, Mo2TiAlC2 has the biggest anisotropy among the three compounds. The results of optical functions indicate that the reflectivity of the three compounds is high in visible-ultraviolet region up to ~10.5 eV under ambient pressure and increasing constantly when under pressure. Mo2TiAlC2 has the highest loss function. The calculated sound velocity and Debye temperature show that they all increase with pressure. CV of the three compounds is also calculated.

  20. High-pressure X-ray study of LiCrSi2O6 clinopyroxene and the general compressibility trends of Li-clinopyroxenes

    DEFF Research Database (Denmark)

    Periotto, Benedetta; Angel, Ross J.; Nestola, Fabrizio

    2013-01-01

    High-pressure single-crystal X-ray diffraction measurements of synthetic LiCrSi2O6 clinopyroxene (with space group P21/c) were performed in a diamond-anvil cell up to 7.970 GPa. No phase transition has been observed within the pressure range investigated, but the elastic behavior at lower pressures...... phase transition above 8 GPa to the HP-C2/c space group. A comparison of the Li-clinopyroxenes (M1 = Cr, Al, Sc, Ga, Mg + Fe) previously investigated and our sample shows that their elastic behavior and structural mechanisms of compression are analogous....... derivative K0 = 8.8(6). The structural data measured up to 7.970 GPa confirm that the space group P21/c is maintained throughout the whole pressure range investigated. The atomic parameters, obtained from the integrated diffraction intensities, suggest that the Li coordination polyhedron changes its...

  1. Searching for “LiCrIIPO4”

    International Nuclear Information System (INIS)

    Mosymow, E.; Glaum, R.; Kremer, R.K.

    2014-01-01

    The two new phosphates LiCr II 4 (PO 4 ) 3 and Li 5 Cr II 2 Cr III (PO 4 ) 4 are discovered as equilibrium phases (ϑ=800 °C) in the quarternary system Li/Cr/P/O. Their crystal structures have been determined from single-crystal X-ray diffraction data (LiCr II 4 (PO 4 ) 3 : violet-blue, Pnma (no. 62), Z=4, a=6.175(1) Å, b=14.316(3) Å, c=10.277(2) Å, 100 parameters, R 1 =0.028, wR 2 =0.08, 2060 unique reflections with F o >4σ(F o ); Li 5 Cr II 2 Cr III (PO 4 ) 4 : greyish-green, P1 ¯ (no. 2), Z=1, a=4.9379(7) Å, b=7.917(2) Å, c=8.426(2) Å, α=109.98(2)°, β=90.71(1)°, γ=104.91(1)°, 131 parameters, R 1 =0.022, wR 2 =0.067, 1594 unique reflections with F o >4σ(F o )). Li 5 Cr II 2 Cr III (PO 4 ) 4 adopts an hitherto unknown structure type. The crystal structure of LiCr II 4 (PO 4 ) 3 is isotypic to that of NaCd II 4 (PO 4 ) 3 and related to that of the mineral silicocarnotite Ca 5 (PO 4 ) 2 (SiO 4 ). Significant disorder between Li + and Cr 2+ is observed for both crystal structures. The oxidation states assigned to chromium in these two phosphates are in agreement with UV/vis/NIR absorption spectra and magnetic susceptibility data recorded for both compounds. Instead of “LiCr II PO 4 ” mixtures of LiCr II 4 (PO 4 ) 3 , Li 5 Cr II 2 Cr III (PO 4 ) 4 , Cr 2 O 3 , and CrP are observed at equilibrium. Instead of “Li 2 Cr II P 2 O 7 ” four-phase mixtures consisting of Li 9 Cr III 3 (P 2 O 7 ) 3 (PO 4 ) 2 , Li 3 Cr III 2 (PO 4 ) 3 , LiCrP 2 O 7 , and CrP were obtained. - Graphical abstract: Investigations on the equilibrium relations in the system Li/Cr/P/O revealed the two hitherto unknown phosphates Li 5 Cr II 2 Cr III (PO 4 ) 4 and LiCr II 4 (PO 4 ) 3 . They form instead of “LiCr II PO 4 ”. The crystal structures, magnetic behavior and optical spectra of these phosphates are reported. - Highlights: • The two new phosphates Li 5 Cr II 2 Cr III (PO 4 ) 4 and LiCr II 4 (PO 4 ) 3 have been characterized. • Optical spectra and paramagnetism of

  2. Microscale fracture mechanisms of a Cr3C2-NiCr HVOF coating

    International Nuclear Information System (INIS)

    Robertson, Andrew L.; White, Ken W.

    2017-01-01

    Thermal spray coatings, often composed of heterogeneous, multiphase microstructures, may, consequently, exhibit complex fracture behavior. For such coating structures, conventional mechanical evaluation methods fail to isolate the contribution of microstructural features to the overall fracture behavior. For this reason, this study employed focused ion beam machined (FIB) microcantilever beams and FIB sectioning methods to study the fracture mechanisms important at the scale of the heterogeneous Cr 3 C 2 -NiCr thermal spray coating. We found three fracture modes, namely, intergranular matrix fracture, matrix/carbide interfacial fracture, and carbide cleavage. By comparison, microindentation-induced cracks, the frequency of crack deflection around carbides is significantly more prevalent at this much larger crack dimension. This mechanistic variation provides some insight into the specific role and limitations of the microcantilever beam technique for fracture characterization of composite microstructures.

  3. Nanometre-scale 3D defects in Cr2AlC thin films.

    Science.gov (United States)

    Chen, Y T; Music, D; Shang, L; Mayer, J; Schneider, J M

    2017-04-20

    MAX-phase Cr 2 AlC containing thin films were synthesized by magnetron sputtering in an industrial system. Nanometre-scale 3D defects are observed near the boundary between regions of Cr 2 AlC and of the disordered solid solution (CrAl) x C y . Shrinkage of the Cr-Cr interplanar distance and elongation of the Cr-Al distance in the vicinity of the defects are detected using transmission electron microscopy. The here observed deformation surrounding the defects was described using density functional theory by comparing the DOS of bulk Cr 2 AlC with the DOS of a strained and unstrained Cr 2 AlC(0001) surface. From the partial density of states analysis, it can be learned that Cr-C bonds are stronger than Cr-Al bonds in bulk Cr 2 AlC. Upon Cr 2 AlC(0001) surface formation, both bonds are weakened. While the Cr-C bonds recover their bulk strength as Cr 2 AlC(0001) is strained, the Cr-Al bonds experience only a partial recovery, still being weaker than their bulk counterparts. Hence, the strain induced bond strengthening in Cr 2 AlC(0001) is larger for Cr d - C p bonds than for Cr d - Al p bonds. The here observed changes in bonding due to the formation of a strained surface are consistent with the experimentally observed elongation of the Cr-Al distance in the vicinity of nm-scale 3D defects in Cr 2 AlC thin films.

  4. X-ray fluorescence analysis of Cr6+ component in mixtures of Cr2O3 and K2CrO4

    International Nuclear Information System (INIS)

    Tochio, Tatsunori; Sakakura, Shusuke; Oohashi, Hirofumi

    2010-01-01

    X-ray fluorescence analysis using Cr K α spectra was applied to the determination of the mixing ratio of Cr 6+ to (Cr 6+ + Cr 3+ ) in several mixtures of K 2 CrO 4 and Cr 2 O 3 . Because the powder of K 2 CrO 4 contained large particles that were more than 50 μm in diameter, it was ground between a pestle and a mortar for about 8 h. The coarse particles still remaining were removed by using a sieve with 325-mesh (44 μm) in order to reduce the difference in absorption effects between emissions from Cr 6+ and those from Cr 3+ . The mixing ratio, K 2 CrO 4 /(K 2 CrO 4 + Cr 2 O 3 ), of the five mixtures investigated is 0.50, 0.40, 0.20, 0.10, and 0.05 in weight, respectively. Each spectrum obtained was analyzed by decomposing it into two reference spectra, those of the two pure materials, K 2 CrO 4 and Cr 2 O 3 , with a constant background. The results for the mixtures containing K 2 CrO 4 of more than 20 wt% are that the relative deviation from the true value is less than ∼5%. On the other hand, when the content of K 2 CrO 4 decreases to less than 10 wt%, the relative deviation gets so large as 20 - 25%. The error coming from a peak separation of spectrum involved in our results were estimated by applying our method to five sets of data for each mixture computationally generated, taking into account the uncertainty in total counts of real measurements. (author)

  5. X-ray fluorescence analysis of Cr(6+) component in mixtures of Cr(2)O(3) and K(2)CrO(4).

    Science.gov (United States)

    Tochio, Tatsunori; Sakakura, Shusuke; Oohashi, Hirofumi; Mizota, Hirohisa; Zou, Yanhui; Ito, Yoshiaki; Fukushima, Sei; Tanuma, Shigeo; Shoji, Takashi; Fujimura, Hajime; Yamashita, Michiru

    2010-01-01

    X-ray fluorescence analysis using Cr K(alpha) spectra was applied to the determination of the mixing ratio of Cr(6+) to (Cr(6+) + Cr(3+)) in several mixtures of K(2)CrO(4) and Cr(2)O(3). Because the powder of K(2)CrO(4) contained large particles that were more than 50 microm in diameter, it was ground between a pestle and a mortar for about 8 h. The coarse particles still remaining were removed by using a sieve with 325-mesh (44 microm) in order to reduce the difference in absorption effects between emissions from Cr(6+) and those from Cr(3+). The mixing ratio, K(2)CrO(4)/(K(2)CrO(4) + Cr(2)O(3)), of the five mixtures investigated is 0.50, 0.40, 0.20, 0.10, and 0.05 in weight, respectively. Each spectrum obtained was analyzed by decomposing it into two reference spectra, those of the two pure materials, K(2)CrO(4) and Cr(2)O(3), with a constant background. The results for the mixtures containing K(2)CrO(4) of more than 20 wt% are that the relative deviation from the true value is less than approximately 5%. On the other hand, when the content of K(2)CrO(4) decreases to less than 10 wt%, the relative deviation gets so large as 20 - 25%. The error coming from a peak separation of spectrum involved in our results were estimated by applying our method to five sets of data for each mixture computationally generated, taking into account the uncertainty in total counts of real measurements.

  6. microstructure change in 12 % Cr steel during creep

    International Nuclear Information System (INIS)

    Winatapura, D. S.; Panjaitan, E.; Arslan, A.; Sulistioso, G.S.

    1998-01-01

    The microstructure change in steel containing of 12% Cr or DIN X20CrMoV 12 1 during creep has been studied by means of optical microscopy and Transmission Electron Microscope (TEM). The creep testing at 650 o C was conducted under constant load of 650 Mpa. The heat treatment of the specimen before creep testing was austenization, followed by tempering for 2 hours. The obtained microstructure was tempered martensitic. This microstructure consisted of the martensite laths, and distributed randomly in the matrix. During tempering, chromium carbide particles of Cr 7 C 6 less than 0,2 μmin-size were precipitated on or and in the subgrain and lath martensite grain boundary. During creep testing those particles transformed and precipitated as chrome carbide precipitates of Cr 23 C 6 . At the secondary creep stage, the void formation occurred, and then it developed into the creep cracks. At tertiary creep stage for 3554 hours, the specimen was failure. The creep cracks were informs of transgranular and intergranular modes which propagated almost perpendicular to the stress axis. From this observation, it is suggested that tempering caused the ductility of martensitic microstructure, which increased the creep resistant or Cr 12% steel

  7. Structure and molecular motion in three modifications of a binary C23H48-C24H50 paraffin

    International Nuclear Information System (INIS)

    Craievich, A.F.; Denicolo, I.; Doucet, J.

    1983-01-01

    The temperature dependence of the intensities of the (00l) X-ray reflections from a binary paraffin (C 23 H 48 -25% C 24 H 50 ) was determined, in order to obtain structure parameters related to the molecular motion and intramolecular defects. The long lattice spacing was also determined as a function of the temperature. All of these results are compared with the temperature dependence of the ratio of the two short lattice parameters. The clear correlation of all of these experimental results provides a close characterization of the molecular structures and their changes at the several solid state phase transitions. (Author) [pt

  8. Substitution and diffusion of Cr 2+ and Cr 3+ in synthetic forsterite and natural olivine at 1200–1500 °C and 1 bar

    Energy Technology Data Exchange (ETDEWEB)

    Jollands, M. C.; O' Neill, H. St. C.; Van Orman, J.; Berry, A. J.; Hermann, J.; Newville, M.; Lanzirotti, A.

    2018-01-01

    The diffusion and substitution mechanisms of Cr in forsterite were studied as a function of crystallographic orientation and the chemical potentials of all four components in the system MgO-SiO2-Cr-O. Oxygen fugacity (fO2) was varied over 15.4 log units at 1400 °C and was fixed at the iron-wüstite equilibrium for a temperature series (1200–1500 °C). The valence state changes of Cr along some diffusion profiles was also investigated using X-ray absorption near edge structure spectroscopy.

  9. Ultraviolet magnetic circular dichroism study and x-ray absorption spectroscopy of zinc-blende type CrAs multilayer

    International Nuclear Information System (INIS)

    Mizuguchi, M.; Manago, T.; Akinaga, H.; Yamada, T.; Yagi-Watanabe, K.; Yuri, M.; Chen, C.T.; Shirai, M.

    2004-01-01

    Full text: Half-metallic ferromagnets such as CrO 2 and Heusler alloys have attracted a great deal of attention due to its application to spin-dependent device. We have predicted by first principle calculations that zinc-blende (zb) type CrAs, which normally exists in a MnP type, shows a half-metallic band structure, and succeeded in fabrication of this film. However, the epitaxial growth with maintaining a zb structure was limited up to around the nominal thickness of 3 nm. In this contribution, ultraviolet magnetic circular dichroism (MCD) and x-ray absorption spectroscopy (XAS) of CrAs multilayers are reported. These multilayers include zb-CrAs layers and low-temperature GaAs layers stacked alternately, and total thicknesses of zb- CrAs are thicker than 3 nm. Incident beam with the photon energy from 4 to 8 eV were used, and samples were attached on a magnet with the magnetic field of 1.0 T for the MCD measurements. Strong signal with the peak top at 6.5 eV is observed in the MCD spectrum. It can be seen that the experimental spectrum has a good agreement with the theoretical one, which indicates the formation of a superstructure as designed. It was also clarified by the XAS measurement using incident beam from 560 to 600 eV that peak positions of these multilayers shift systematically according to the thickness of each layer. The CrAs/GaAs multilayer is also expected to possess a half-metallic property by the theoretical calculation, therefore, the present result shows the multilayer will be the promising candidate as the spin electronics material

  10. Electrically active defects in n-type 4H- and 6H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, J.P. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics]|[IBM Research Div., T.J. Watson Research Center, Yorktown Heights, NY (United States); Aboelfotoh, M.O. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics]|[North Carolina State Univ., Dept. of Materials Science and Engineering, Raleigh, NC (United States); Svensson, B.G. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics

    1998-06-01

    We have found that in 6H-SiC, irradiation induced defects can become mobile at temperatures as low as 200 C. Through isochronal and isothermal annealing a level at 0.51 eV below the conduction band (with a capture cross-section of 2 x 10{sup -14} cm{sup 2}), appears to disassociate through a first order process with an activation energy of 1.45 eV+/-0.1 eV. In 4H-SiC, we have observed two irradiation induced defects assigned the positions 0.62 eV and 0.68 eV below E{sub c} (with capture cross-sections of 4 x 10{sup -14} cm{sup 2} and 5 x 10{sup -15} cm{sup 2}, respectively) which are found to be unstable at room temperature with time. SIMS analysis indicates that in both 6H- and 4H-SiC the defect levels are not due to the incorporation of the transition metals Ti, V, or Cr. Additionally, in both polytypes of SiC that were examined, the defects are found to display acceptor-like behavior as no evidence of a Poole-Frenkel shift was observed during DLTS measurements. (orig.) 10 refs.

  11. Growth of Sr2CrReO6 epitaxial thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    Orna, J.; Morellon, L.; Algarabel, P.A.; Pardo, J.A.; Magen, C.; Varela, M.; Pennycook, S.J.; De Teresa, J.M.; Ibarra, M.R.

    2010-01-01

    We report the growth, structural, magnetic, and electrical transport properties of epitaxial Sr 2 CrReO 6 thin films. We have succeeded in depositing films with a high crystallinity and a relatively large cationic order in a narrow window of growth parameters. The epitaxy relationship is Sr 2 CrReO 6 (SCRO) (0 0 1) [1 0 0]-parallel SrTiO 3 (STO) (0 0 1) [1 1 0] as determined by high-resolution X-ray diffraction and scanning transmission electron microscopy (STEM). Typical values of saturation magnetization of M S (300 K)=1 μ B /f.u. and ρ (300 K)=2.8 mΩ cm have been obtained in good agreement with previous published results in sputtered epitaxial thin films. We estimate that the antisite defects concentration in our thin films is of the order of 14%, and the measured Curie temperature is T C =481(2) K. We believe these materials be of interest as electrodes in spintronic devices.

  12. PET Imaging of CRF1 with [11C]R121920 and [11C]DMP696: is the target of sufficient density?

    International Nuclear Information System (INIS)

    Sullivan, Gregory M.; Parsey, Ramin V.; Kumar, J.S. Dileep; Arango, Victoria; Kassir, Suham A.; Huang, Yung-yu; Simpson, Norman R.; Van Heertum, Ronald L.; Mann, J. John

    2007-01-01

    Aim: Overstimulation of the CRF type 1 receptor (CRF1) is implicated in anxiety and depressive disorders. The aim of this study was to investigate the in vivo binding characteristics of [ 11 C]R121920 and [ 11 C]DMP696 in the nonhuman primate for application in positron emission tomography (PET) studies of CRF1. Methods: PET imaging with the two novel CRF1 radioligands was performed in baboon. In vitro binding studies for CRF1 were performed in postmortem brain tissue of baboon and human to assess sufficiency of receptor density for PET. Results: Both [ 11 C]R121920 and [ 11 C]DMP696 distributed rapidly and uniformly throughout the brain. Washout was comparable across brain regions, without differences in volume of distribution between regions reported to have high and low in vitro CRF1 binding. Membrane-enriched tissue homogenate assay using [ 125 I]Tyr 0 -sauvagine and specific CRF1 antagonists CP154,526 and SN003 in human occipital cortex yielded maximal binding (B max ) of 63.3 and 147.3 fmol/mg protein, respectively, and in human cerebellar cortex yielded B max of 103.6 and 64.6 fmol/mg protein, respectively. Dissociation constants (K D ) were subnanomolar. In baboon, specific binding was not detectable in the same regions; therefore, B max and K D were not measurable. Autoradiographic results were consistent except there was also detectable CRF1-specific binding in baboon cerebellum. Conclusion: Neither [ 11 C]R121920 nor [ 11 C]DMP696 demonstrated quantifiable regional binding in vivo in baboon. In vitro results suggest CRF1 density in baboon may be insufficient for PET. Studies in man may generate more promising results due to the higher CRF1 density compared with baboon in cerebral cortex and cerebellum

  13. Epitaxial Bi2 FeCrO6 Multiferroic Thin Film as a New Visible Light Absorbing Photocathode Material.

    Science.gov (United States)

    Li, Shun; AlOtaibi, Bandar; Huang, Wei; Mi, Zetian; Serpone, Nick; Nechache, Riad; Rosei, Federico

    2015-08-26

    Ferroelectric materials have been studied increasingly for solar energy conversion technologies due to the efficient charge separation driven by the polarization induced internal electric field. However, their insufficient conversion efficiency is still a major challenge. Here, a photocathode material of epitaxial double perovskite Bi(2) FeCrO(6) multiferroic thin film is reported with a suitable conduction band position and small bandgap (1.9-2.1 eV), for visible-light-driven reduction of water to hydrogen. Photoelectrochemical measurements show that the highest photocurrent density up to -1.02 mA cm(-2) at a potential of -0.97 V versus reversible hydrogen electrode is obtained in p-type Bi(2) FeCrO(6) thin film photocathode grown on SrTiO(3) substrate under AM 1.5G simulated sunlight. In addition, a twofold enhancement of photocurrent density is obtained after negatively poling the Bi(2) FeCrO(6) thin film, as a result of modulation of the band structure by suitable control of the internal electric field gradient originating from the ferroelectric polarization in the Bi(2) FeCrO(6) films. The findings validate the use of multiferroic Bi(2) FeCrO(6) thin films as photocathode materials, and also prove that the manipulation of internal fields through polarization in ferroelectric materials is a promising strategy for the design of improved photoelectrodes and smart devices for solar energy conversion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Microstructural characterization of Y2O3 ODS-Fe-Cr model alloys

    International Nuclear Information System (INIS)

    Castro, V. de; Leguey, T.; Munoz, A.; Monge, M.A.; Pareja, R.; Marquis, E.A.; Lozano-Perez, S.; Jenkins, M.L.

    2009-01-01

    Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y 2 O 3 and the other Y 2 O 3 -free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes 3 C and M 23 C 6 carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M 23 C 6 carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.

  15. Structure and Function of p97 and Pex1/6 Type II AAA+ Complexes.

    Science.gov (United States)

    Saffert, Paul; Enenkel, Cordula; Wendler, Petra

    2017-01-01

    Protein complexes of the Type II AAA+ (ATPases associated with diverse cellular activities) family are typically hexamers of 80-150 kDa protomers that harbor two AAA+ ATPase domains. They form double ring assemblies flanked by associated domains, which can be N-terminal, intercalated or C-terminal to the ATPase domains. Most prominent members of this family include NSF (N-ethyl-maleimide sensitive factor), p97/VCP (valosin-containing protein), the Pex1/Pex6 complex and Hsp104 in eukaryotes and ClpB in bacteria. Tremendous efforts have been undertaken to understand the conformational dynamics of protein remodeling type II AAA+ complexes. A uniform mode of action has not been derived from these works. This review focuses on p97/VCP and the Pex1/6 complex, which both structurally remodel ubiquitinated substrate proteins. P97/VCP plays a role in many processes, including ER- associated protein degradation, and the Pex1/Pex6 complex dislocates and recycles the transport receptor Pex5 from the peroxisomal membrane during peroxisomal protein import. We give an introduction into existing knowledge about the biochemical and cellular activities of the complexes before discussing structural information. We particularly emphasize recent electron microscopy structures of the two AAA+ complexes and summarize their structural differences.

  16. Syntheses of [6-14C] and [5-carboxy, 6-14C2]nitrendipine

    International Nuclear Information System (INIS)

    Maul, N.; Scherling, D.

    1989-01-01

    [6- 14 C]Nitrendipine synthesis started from barium[ 14 ]carbonate, which was converted to [1- 14 C]acetyl chloride. The acid chloride was condensed with Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione). The resulting intermediate was treated with boiling methanol to give methyl [3- 14 C]acetoacetate. The reaction with gaseous ammonia in toluene yielded the corresponding methyl 3-amino[3- 14 C]crotonate which was condensed with ethyl 2-(3-nitro-benzylidene) acetoacetate to obtain [6- 14 C]nitrendipine. (author)

  17. Structure and grindability of cast Ti-5Cr-xFe alloys

    International Nuclear Information System (INIS)

    Hsu, H.-C.; Pan, C.-H.; Wu, S.-C.; Ho, W.-F.

    2009-01-01

    The purpose of this study was to investigate the structure, microhardness and grindability of Ti-5Cr and a series of ternary Ti-5Cr-xFe alloys with 0.1, 0.5, 1, 3 and 5 wt.% Fe, respectively. This study evaluated the phase and structure of Ti-5Cr and Ti-5Cr-xFe alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. In addition, grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min at each of the four rotational speeds of the wheel (500, 750, 1000 or 1200 m/min), with the goal of developing a titanium alloy with better machinability than commercially pure titanium (c.p. Ti). The results showed that the structure of Ti-5Cr-xFe alloys is sensitive to the Fe content. With Fe contents higher than 0.5 wt.%, the equi-axed β phase is entirely retained, while ω phase was found in the Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The largest quantity of ω phase and highest microhardness were found in Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The grinding rates of the Ti-5Cr and Ti-5Cr-xFe alloys showed a similar tendency to the microhardness. The Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys exhibited the best grindability, especially at 500, 750 and 1000 m/min. Furthermore, the grindability of the tested metals increased in proportion to grinding speed up to 1000 m/min, with a decrease after 1200 m/min. This study concluded that Fe may be used to harden titanium and improve the grindability

  18. PENGAMBILAN LOGAM CR6+ DAN CR TOTAL DARI LIMBAH INDUSTRI ELEKTROPLATING SECARA ELEKTROKOGULASI

    Directory of Open Access Journals (Sweden)

    Muhammad Nizar Pahlevi

    2012-10-01

    Full Text Available Electroplating industry is a metal coating industry by way of metal precipitate coatings on metal or plastic which is done so that the electrolytic waste containing heavy metals. Electrocoagulation is a process of merging clumps resulting from the flux of electrical current (DC for the extraction of metal compounds contained in wastewater. In this process of reduction and oxidation reactions occur. Where the metal is reduced and the positive electrode (Al will be oxidized to (Al (OH 3 which serves as a coagulant. The purpose of this research to study methods of electrocoagulation using aluminum electrodes and the influence of the length of time stirring and stirring speed of decision-CR6+ levels and total Cr. This electrocoagulation electroplating wastewater with electricity so that the ions are absorbed by the coagulant in waste binder in the release of the electrode and causes the bond between the metal ions with coagulant. Variation of stirrer speed of 200, 400 and 600 rpm, whereas the long stirring time 25, 50 and 75 minutes. Based on test results, after an analysis showed a significant reduction of the levels of total CR6 + and Cr in the electroplating wastes. CR6+ to obtain a decrease of 95.1% at minute 50 and the stirrer speed of 200 rpm, whereas the total Cr obtained a decrease of 82.69% at minute 75 and a stirrer speed of 600 rpm.

  19. NQR and X-ray crystal structure studies of cadmium halide complexes: [C(NH2)3]CdI3 and [4-ClC6H5NH3]3CdBr5

    International Nuclear Information System (INIS)

    Gesing, Thorsten M.; Lork, Enno; Terao, Hiromitsu; Ishihara, Hideta

    2016-01-01

    The crystal structures of [C(NH 2 ) 3 ]CdI 3 (1) and [4-ClC 6 H 5 NH 3 ] 3 CdBr 5 (2) have been determined at 100 K: monoclinic, Cc, a = 828.75(3) pm, b = 1615.31(5) pm, c = 810.64(3) pm, and β = 106.5820(10) for 1; monoclinic, P2 1 /c, a = 1486.93(5) pm, b = 794.31(3) pm, c = 2290.59(7) pm, and β = 99.6830(10) for 2. The structure of 1 has an infinite chain of anions consisting of [CdI 4 ] tetrahedra sharing two corners. The structure of 2 has an infinite chain of anions consisting of [CdBr 6 ] octahedra sharing two corners in cis positions. In both structures, isolated cations are connected to the anion chains through weak hydrogen bonds Cd-X..H to result in three-dimensional network structures. In accordance with the crystal structures, three 127 I (m = ±1/2 <-> m = ±3/2), five 81 Br, and three 35 Cl nuclear quadrupole resonance (NQR) lines were observed for 1 and 2. The NQR spectra reflect the anion chain structures and their weak hydrogen bonds. The MO calculations of the models [Cd 5 I 16 ] 6- for 1 and [Cd 3 Br 16 ] 10- for 2 estimate only about half the values for the NQR frequencies but give accurate electric field gradient directions.

  20. Fired products of Cr-smectite clays in nitrogen

    Directory of Open Access Journals (Sweden)

    C. Volzone

    2004-12-01

    Full Text Available The products of Cr-smectite clays heated to 1350 ° C in nitrogen were evaluated by X-ray diffraction and chemical analysis. Cr-smectite clays were prepared at room temperature by contact between smectite clays and Cr species contained in OH-Cr solutions. The Cr species were prepared using chromium nitrate solution by addition of NaOH solution with OH/Cr = 2. Products of firing in nitrogen at the high temperature were different (magnesia chromite, donathite, iron chromium oxide and picrochromite depending on the type of isomorphous substitution of the smectite structure and the amount of retained chromium.

  1. Subaortic (Type 6 Muscular Band—Innocent Bystander or Pathologic Structure?

    Directory of Open Access Journals (Sweden)

    J Ker

    2010-08-01

    Full Text Available Intraventricular tendons are structures that was identified more than a hundred years ago. It has been suggested that they represent intracavitary radiations of the bundle of His and that they may be an isolated finding or be associated with structural cardiac abnormalities. Loukas et al divided these structures into five categories and recently a sixth type have been added. Various physiological disturbances have been observed due to the sixth type of tendon, such as ST segment elevation and right bundle branch block. It has been noted that this peculiar structure appears too thick to be called a tendon, thus the term band. This retrospective analysis analyzed the incidence of the thick, subaortic (type 6 muscular band in a cardiovascular clinic.

  2. Structural Disorder and Magnetism in the Spin-Gapless Semiconductor CoFeCrAl

    Science.gov (United States)

    2016-08-24

    distinguishes two types of occupancies (Fe-Co and Cr-Al) and the fcc (A2) structure is completely random with respect to atomic positions. II. RESULTS AND...Physical Properties Measurement system (PPMS). Figures 2(a) shows the x-ray diffraction pattern for the sample annealed at 450 ◦C as well as the fit and... measure - ments. A favorable feature of the Si-substituted alloy is the increase of the minority band gap from 0.30 eV to 0.43 eV. ACKNOWLEDGEMENT

  3. Elastic properties of nanolaminar Cr_2AlC films and beams determined by in-situ scanning electron microscope bending tests

    International Nuclear Information System (INIS)

    Grieseler, Rolf; Theska, Felix; Stürzel, Thomas; Hähnlein, Bernd; Stubenrauch, Mike; Hopfeld, Marcus; Kups, Thomas; Pezoldt, Jörg; Schaaf, Peter

    2016-01-01

    The mechanical properties of Cr_2AlC MAX phase structures were investigated by in-situ bending tests. Freestanding structures such as cantilevers and doubly clamped beams of Cr_2AlC were produced. The structures exhibit a Young's modulus of 184 GPa which is close to the value obtained by vibrational measurements. The in-situ bending test allows the determination of the mechanical properties with a lower variance of the measurement results compared to the vibrational measurement. The results are a good starting point for the development of microelectromechanical structures based on MAX phases. - Highlights: • Cr_2AlC were produced by deposition multilayers and subsequent rapid annealing. • Freestanding doubly clamped beams and cantilevers of Cr_2AlC were prepared. • A finite elements model was implemented showing the displacement of the structure. • In-situ bending test at doubly clamped beams and cantilevers were performed. • An in-situ bending test is a valid approach to determine mechanical properties.

  4. High-Pressure Phase Relations and Crystal Structures of Postspinel Phases in MgV2O4, FeV2O4, and MnCr2O4: Crystal Chemistry of AB2O4 Postspinel Compounds.

    Science.gov (United States)

    Ishii, Takayuki; Sakai, Tsubasa; Kojitani, Hiroshi; Mori, Daisuke; Inaguma, Yoshiyuki; Matsushita, Yoshitaka; Yamaura, Kazunari; Akaogi, Masaki

    2018-06-04

    We have investigated high-pressure, high-temperature phase transitions of spinel (Sp)-type MgV 2 O 4 , FeV 2 O 4 , and MnCr 2 O 4 . At 1200-1800 °C, MgV 2 O 4 Sp decomposes at 4-7 GPa into a phase assemblage of MgO periclase + corundum (Cor)-type V 2 O 3 , and they react at 10-15 GPa to form a phase with a calcium titanite (CT)-type structure. FeV 2 O 4 Sp transforms to CT-type FeV 2 O 4 at 12 GPa via decomposition phases of FeO wüstite + Cor-type V 2 O 3 . MnCr 2 O 4 Sp directly transforms to the calcium ferrite (CF)-structured phase at 10 GPa and 1000-1400 °C. Rietveld refinements of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 confirm that both the CT- and CF-type structures have frameworks formed by double chains of edge-shared B 3+ O 6 octahedra (B 3+ = V 3+ and Cr 3+ ) running parallel to one of orthorhombic cell axes. A relatively large A 2+ cation (A 2+ = Mg 2+ , Fe 2+ , and Mn 2+ ) occupies a tunnel-shaped space formed by corner-sharing of four double chains. Effective coordination numbers calculated from eight neighboring oxygen-A 2+ cation distances of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 are 5.50, 5.16, and 7.52, respectively. This implies that the CT- and CF-type structures practically have trigonal prism (six-coordinated) and bicapped trigonal prism (eight-coordinated) sites for the A 2+ cations, respectively. A relationship between cation sizes of VIII A 2+ and VI B 3+ and crystal structures (CF- and CT-types) of A 2+ B 2 3+ O 4 is discussed using the above new data and available previous data of the postspinel phases. We found that CF-type A 2+ B 2 3+ O 4 crystallize in wide ionic radius ranges of 0.9-1.4 Å for VIII A 2+ and 0.55-1.1 Å for VI B 3+ , whereas CT-type phases crystallize in very narrow ionic radius ranges of ∼0.9 Å for VIII A 2+ and 0.6-0.65 Å for VI B 3+ . This would be attributed to the fact that the tunnel space of CT-type structure is geometrically less flexible due to the smaller coordination

  5. Nido-Carborane building-block reagents. 2. Bulky-substituent (alkyl)2C2B4H6 derivatives and (C6H5)2C2B4H6: synthesis and properties

    International Nuclear Information System (INIS)

    Boyter, H.A. Jr.; Grimes, R.N.

    1988-01-01

    The preparation and chemistry of nido-2,3-R 2 C 2 C 2 B 4 H 6 carboranes in which R is n-butyl, isopentyl, n-hexyl, and phenyl was investigated in order to further assess the steric and electronic influence of the R groups on the properties of the nido-C 2 B 4 cage, especially with respect to metal complexation at the C 2 B 3 face and metal-promoted oxidative fusion. The three dialkyl derivatives were prepared from the corresponding dialkylacetylenes via reaction with B 5 H 9 and triethylamine, but the diphenyl compound could not be prepared in this manner and was obtained instead in a thermal reaction of B 5 H 9 with diphenylacetylene in the absence of amine. All four carboranes are readily bridge-deprotonated by NaH in THF, and the anions of the dialkyl species, on treatment with FeCl 2 and air oxidation, generate the respective R 4 C 4 B 8 H 8 carborane fusion products were R = n-C 4 H 9 , i-C 5 H 11 or n-C 6 H 13 . The diphenylcarborane anion Ph 2 C 2 B 4 H 5 - did not form detectable metal complexes with Fe 2+ , Co 2+ , or Ni 2+ , and no evidence of a Ph 4 C 4 B 8 H 8 fusion product has been found. Treatment of Ph 2 C 2 B 4 H 6 with Cr(CO) 6 did not lead to metal coordination of the phenyl rings, unlike (PhCH 2 ) 2 C 2 B 4 H 6 , which had previously been shown to form mono- and bis(tricarbonylchromium) complexes. However, the reaction of Ph 2 C 2 B 4 H 5 - , CoCl 2 , and (PhPCH 2 ) 2 did give 1,1-(Ph 2 PCH 2 ) 2 -1-Cl-1,2,3-Co(Ph 2 C 2 B 4 H 4 ), the only case in which metal complexation of the diphenylcarborane was observed. 14 references, 3 figures, 3 tables

  6. Preparation and characterization of the electrodeposited Cr-Al{sub 2}O{sub 3}/SiC composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Gao Jifeng, E-mail: readlot@tom.com [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Suo Jinping, E-mail: jpsuo@yahoo.com.cn [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-09-01

    To increase the SiC content in Cr-based coatings, Cr-Al{sub 2}O{sub 3}/SiC composite coatings were plated in Cr(VI) baths which contained Al{sub 2}O{sub 3}-coated SiC powders. The Al{sub 2}O{sub 3}-coated SiC composite particles were synthesized by calcining the precursor prepared by heterogeneous deposition method. The transmission electron microscopy analysis of the particles showed that the nano-SiC particle was packaged by alumina. The zeta potential of the particles collected from the bath was up to +23 mV, a favorable condition for the co-deposition of the particles and chromium. Pulse current was used during the electrodeposition. Scanning Electron Microscopy (SEM) indicated that the coating was compact and combined well with the substrate. Energy dispersive X-ray analysis of Cr-Al{sub 2}O{sub 3}/SiC coatings demonstrated that the concentration of SiC in the coating reached about 2.5 wt.%. The corrosion behavior of the composite coating was studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The data obtained suggested that the Al{sub 2}O{sub 3}/SiC particles significantly enhanced the corrosion resistance of the composite coating in 0.05 M HCl solution.

  7. Characterisation of the Microstructure of Fe–Al/Cr3C2 Composite Coatings

    Science.gov (United States)

    Liu, Xiaoming; JunhuiDong; Yang, Yuehong; Sun, Changming; Tuo, Ya; Li, Yanwei

    2018-03-01

    An Fe-Al/Cr3C2 composite coating is investigated to assess its suitability for treating high-temperature components in a power plant. The coating exhibits excellent high- temperature properties including good corrosion, erosion and friction-wear resistance at high temperatures. To deduce the formation of the Fe-Al/Cr3C2 composite coating and to provide an adequate theoretical basis for its extensive application, its structures and microstructures are investigated. Scanning electronic microscopy (SEM)is used along with energy-dispersive X-ray analysis (EDAX) to analyse the surface of the coating. Energy-dispersive spectroscopy (EDS) is used to analyse the cross-section of the coating. Further, X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to analyse the phases and micro structural features within the coating. The results reveal that the basic phases are two orderly inter metallic compounds (Fe3Al and FeAl) and that the reinforcement includes two oxides (Al2O3 and Cr2O3) as well as substantial quantities of Cr3C2. Al2O3is formed using two mechanisms: oxidation of aluminium in the coating and separation of Al2O3crystals from Fe3Al and FeAl. The grain size of Al2O3 and Cr2O3 in the coatings is nanometric. These two oxides may increase the corrosion-erosion and wear resistances of the coating when they are used as reinforcements.

  8. The electronic structure of the metastable layer compound 1T-CrSe2

    NARCIS (Netherlands)

    Fang, C.M.; Groot, R.A. de; Wiegers, G.A.; Haas, C.; vanBruggen, C.F.; deGroot, R.A.

    1997-01-01

    The electronic structure of the metastable compound 1T-CrSe2 (a = 3.399 Å, c = 5.911 Å, space group P_3m1) was calculated with and without spin polarization using the LSW method. The energy is 0.29 eV/mol CrSe2 lower for the spin-polarized calculation. The total magnetic moment of +2.44 μB on Cr

  9. 钛合金表面激光熔覆NiCrBSi(Ti)-TiC涂层%Study on laser cladding of NiCrBSi (Ti)-TiC metal-ceramiccomposite coatings on titanium alloy

    Institute of Scientific and Technical Information of China (English)

    孙荣禄; 郭立新; 董尚利; 杨德庄

    2001-01-01

    在TC4合金表面进行了激光熔覆NiCrBSi-TiC,Ti-TiC金属陶瓷复合涂层的试验,对涂层的组织和显微硬度进行了分析和测试.结果表明,NiCrBSi-TiC涂层的组织是在初晶γ-Ni和γ-Ni,Ni3B,M23(CB)6,CrB多元共晶的基底上均匀地分布着TiC颗粒,在激光熔覆过程中TiC颗粒只是边缘发生了溶解或熔化;在Ti-TiC涂层中,TiC颗粒全部溶解或熔化,冷却时以枝晶形式重新析出.NiCrBSi-TiC涂层的显微硬度(HV900~1100)明显高于Ti-TiC的涂层的显微硬度(HV500~700).

  10. Comparative study on stress in AlGaN/GaN HEMT structures grown on 6H-SiC, Si and on composite substrates of the 6H-SiC/poly-SiC and Si/poly-SiC

    International Nuclear Information System (INIS)

    Guziewicz, M; Kaminska, E; Piotrowska, A; Golaszewska, K; Domagala, J Z; Poisson, M-A; Lahreche, H; Langer, R; Bove, P

    2008-01-01

    The stresses in GaN-based HEMT structures grown on both single crystal 6H SiC(0001) and Si(111) have been compared to these in the HEMT structures grown on new composite substrates engendered as a thin monocrystalline film attached to polycrystalline 3C-SiC substrate. By using HRXRD technique and wafer curvature method we show that stress of monocrystalline layer in composite substrates of the type mono-Si/poly-SiC is lower than 100 MPa and residual stress of epitaxial GaN buffer grown on the composite substrate does not exceed 0.31 GPa, but in the cases of single crystal SiC or Si substrates the GaN buffer stress is compressive in the range of -0.5 to -0.75 GPa. The total stress of the HEMT structure calculated from strains is consistent with the averaged stress of the multilayers stack measured by wafer curvature method. The averaged stress of HEMT structure grown on single crystals is higher than those in structures grown on composites substrates

  11. Layered B-site cation ordering: A key factor in ferrimagnetism of Y{sub 2}MnCrO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Lin [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China); Yang, Lei [Collaborative Innovation Center for Magnetoelectric Industry, China Three Gorges University, Yichang, Hubei (China); Lee, Ming-Hsien; Lin, Tseh-Hsing [Department of Physics, Tamkang University, Taipei, Taiwan (China); Zhang, ZhongFeng; Xie, XiangNan [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China); Zhu, Hong, E-mail: zhuh@ustc.edu.cn [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China)

    2014-07-15

    Highlights: • Rietveld refinement and first-principles calculations are performed for Y{sub 2}MnCrO{sub 6}. • The layered B-site cation ordering is a more reliable structure for Y{sub 2}MnCrO{sub 6}. • Y{sub 2}MnCrO{sub 6} has an insulating ferrimagnetism (0 0 1)-ordered ground state. • The layered ordered pattern plays a key role for the ferrimagnetism in Y{sub 2}MnCrO{sub 6}. - Abstract: We report the Rietveld refinement of powder X-ray diffraction (XRD) pattern and first-principles calculations for the half-Cr{sup 3+} doped YMnO{sub 3} compound. The Rietveld refinement results suggest that the compound has a monoclinic structure with the Mn{sup 3+}/Cr{sup 3+} layers alternately stacking along the [0 0 1] direction. The first-principles calculations show that the structure with layered B-site cation ordering has the lowest total energy; meanwhile, the insulating ferrimagnetic state is more favored compared to the ferromagnetic state, which is in agreement with the reported experimental results. Based upon Goodenough’s model of semi-covalent exchange, we argue that the anisotropic magnetic couplings between the Mn{sup 3+}/Cr{sup 3+} cations ordered in layered pattern play an important role for the ferrimagnetism in the compound.

  12. Fracture toughness and sliding properties of magnetron sputtered CrBC and CrBCN coatings

    Science.gov (United States)

    Wang, Qianzhi; Zhou, Fei; Ma, Qiang; Callisti, Mauro; Polcar, Tomas; Yan, Jiwang

    2018-06-01

    CrBC and CrBCN coatings with low and high B contents were deposited on 316L steel and Si wafers using an unbalanced magnetron sputtering system. Mechanical properties including hardness (H), elastic modulus (E) and fracture toughness (KIc) as well as residual stresses (σ) were quantified. A clear correlation between structural, mechanical and tribological properties of coatings was found. In particular, structural analyses indicated that N incorporation in CrBC coatings with high B content caused a significant structural evolution of the nanocomposite structure (crystalline grains embedded into an amorphous matrix) from nc-CrB2/(a-CrBx, a-BCx) to nc-CrN/(a-BCx, a-BN). As a result, the hardness of CrBC coating with high B content decreased from 23.4 to 16.3 GPa but the fracture toughness was enhanced. Consequently, less cracks initiated on CrBCN coatings during tribological tests, which combined with the shielding effect of a-BN on wear debris, led to a low friction coefficient and wear rate.

  13. Multilayer-Forming Behavior of Cr Nitrides and Carbides for Thermoreactive Deposition

    Directory of Open Access Journals (Sweden)

    Kyeongmo Park

    2018-05-01

    Full Text Available The effect of a nitride layer on the forming behavior of CrN and (Cr, Fe7C3 multilayers for thermoreactive deposition (TRD was investigated. Plasma nitriding followed by TRD (PN-TRD produced a larger coating thickness than the case of direct TRD with no plasma nitriding. For PN-TRD, an Fe2-3N layer of 10 μm in thickness was produced on AISI 52100 steels using plasma nitriding, followed by TRD using a mixed powder composed of 30 wt % Cr, 2 wt % NH4Cl, and 68 wt % Al2O3. During TRD at 800 °C, a CrN layer of 2 μm in thickness was formed along with a thin layer of mixed carbide (Cr7C3 and nitride (CrN on top. As the deposition temperature was increased to 950 °C, a new layer of Cr7C3 was formed underneath the outermost layer composed of mixed Cr7C3 and CrN. At 950 °C, a Cr-rich zone indicated a thickness of ~7 μm. As the deposition time increased to 3 h at 950 °C, a new layer of (Cr, Fe7C3 was produced at the interface between the CrN formed at 800 °C and the base metal. This layer formed because of the abundant resources of Cr and C provided from the TRD powder and base metal, respectively. The multilayer and interface were concretely filled without the formation of voids as the TRD time increased to 6 h at 950 °C. The TRD process on a pre-nitrided layer was successfully applied to produce multilayers of CrN and Cr7C3.

  14. Structure and magnetic properties of Gd2Co17-xCr x (1.17 ≤ x ≤ 3.0) compounds

    International Nuclear Information System (INIS)

    Fuquan, B.; Tegus, O.; Dagula, W.; Brueck, E.; Klaasse, J.C.P.; Buschow, K.H.J.

    2007-01-01

    The structure and magnetic properties of Gd 2 Co 17-x Cr x (1.17 ≤ x ≤ 3.0) compounds have been investigated by means of X-ray diffraction (XRD) and magnetization measurements. The powder X-ray diffraction patterns show that all samples crystallize as a single phase with the rhombohedral Th 2 Zn 17 -type structure. The lattice parameters a and the unit cell volume V increases slightly with increasing Cr content, but the c parameter varies in a less simple way with increasing Cr content. The X-ray diffraction patterns of the magnetically aligned samples show that all compounds investigated have uniaxial anisotropy. Spin reorientation phenomena occur in all of the compounds. The Curie temperature T C , the spin reorientation temperature T sr , the spontaneous magnetization M 0 and the saturation magnetization M s decrease with the increasing Cr content. The anisotropy constant K 1 and the anisotropy field B a of the compounds at room temperature reach a maximum for x = 1.76. The M 0 and M s increase with increasing temperature from 5 K to 300 K. The easy-axis anisotropy of all compounds changes to easy-plane anisotropy at low temperatures and the spin reorientation phenomena are more pronounced for low Cr concentration

  15. First-principles investigation of Cr-doped Fe2B: Structural, mechanical, electronic and magnetic properties

    Science.gov (United States)

    Wei, Xiang; Chen, Zhiguo; Zhong, Jue; Wang, Li; Wang, Yipeng; Shu, Zhongliang

    2018-06-01

    The structural, mechanical, electronic and magnetic properties of Fe8-xCrxB4 (x = 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7 and 8) have been investigated by first-principles calculation. It was found that the calculated structural parameters are well consistent with available experimental data. Moreover, all studied compounds are thermodynamically stable phases. On the whole, the moduli of the compounds firstly increase and then decrease with the increase of Cr concentration, whereas the variation of hardness exhibits more fluctuations. All Cr-doped Fe2B have better ductility than Fe2B except Fe2Cr6B4 and Fe5Cr3B4. Interestingly, Fe4Cr4B4 is of not only the slightly larger hardness, but also much better ductility than Fe2B. As the Cr concentration is lower than 20 wt%, the hardness of Cr-doped Fe2B slightly decreases with increasing Cr, whereas the sharply increased hardness of (Fe, Cr)2B in Fe-B alloys or boriding layer should be attributed to the multiple alloying effects resulting from Cr and the other alloying elements. The electronic structures revealed that the Fe-B and/or Cr-B bonds are mainly responsible for their mechanical properties, and the M-N (M = Fe or Cr, N = Fe or Cr) bonds in 〈2 2 0〉 and 〈1 1 3〉 orientations show covalent character. Additionally, the magnetic moments (Ms) of the compounds do not monotonically decrease with increasing Cr.

  16. Annealing effect on the structural and optical properties of Cr/α-Cr2O3 monodispersed particles based solar absorbers

    International Nuclear Information System (INIS)

    Khamlich, S.; McCrindle, R.; Nuru, Z.Y.; Cingo, N.; Maaza, M.

    2013-01-01

    Graphical abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. Highlights: ► Cr/α-Cr 2 O 3 have been deposited by the aqueous chemical growth (ACG) method. ► High temperature annealing affects the optical selectivity of the deposited particles. ► Oxygen diffusion to the interface at high temperature results in the oxidization of the substrate. - Abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. The deposited particles were annealed at various temperatures in a hydrogen atmosphere for 2 h to study the annealing temperature dependence of the structural, chemical and optical properties of the particles grown on tantalum substrates. The deposited Cr/α-Cr 2 O 3 was characterized by X-ray diffraction (XRD), attenuated total reflection (ATR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and diffuse reflectance UV–vis–NIR spectroscopy. The XRD and ATR analysis indicated that by increasing annealing temperature, the particles crystallinity was improved and Ta 2 O 5 was formed around 600 °C, due to the fast oxygen diffusion from the deposited α-Cr 2 O 3 toward the tantalum substrate. The optical measurements show that samples annealed at 400 and 500 °C exhibit the targeted high absorbing optical characteristics of “Black chrome”, while those annealed below 400 °C and above 500 °C show a significant low absorptivity and high emissivity.

  17. Cas5d Protein Processes Pre-crRNA and Assembles into a Cascade-like Interference Complex in Subtype I-C/Dvulg CRISPR-Cas System

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ki Hyun; Haitjema, Charles; Liu, Xueqi; Ding, Fran; Wang, Hongwei; DeLisa, Matthew P.; Ke, Ailong (Yale); (Cornell); (Tsinghua)

    2012-10-10

    Clustered regularly interspaced short palindromic repeats (CRISPRs), together with an operon of CRISPR-associated (Cas) proteins, form an RNA-based prokaryotic immune system against exogenous genetic elements. Cas5 family proteins are found in several type I CRISPR-Cas systems. Here, we report the molecular function of subtype I-C/Dvulg Cas5d from Bacillus halodurans. We show that Cas5d cleaves pre-crRNA into unit length by recognizing both the hairpin structure and the 3 single stranded sequence in the CRISPR repeat region. Cas5d structure reveals a ferredoxin domain-based architecture and a catalytic triad formed by Y46, K116, and H117 residues. We further show that after pre-crRNA processing, Cas5d assembles with crRNA, Csd1, and Csd2 proteins to form a multi-sub-unit interference complex similar to Escherichia coli Cascade (CRISPR-associated complex for antiviral defense) in architecture. Our results suggest that formation of a crRNA-presenting Cascade-like complex is likely a common theme among type I CRISPR subtypes.

  18. Bismuth zinc vanadate, BiZn{sub 2}VO{sub 6}: New crystal structure type and electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Eliziario Nunes, Sayonara [Department of Chemistry, Durham University, South Road, Durham DH1 3LE (United Kingdom); Department of Materials Engineering, Federal University of São Carlos, 13565-905 São Carlos, SP (Brazil); Wang, Chun-Hai; So, Karwei; Evans, John S.O. [Department of Chemistry, Durham University, South Road, Durham DH1 3LE (United Kingdom); Evans, Ivana Radosavljević, E-mail: ivana.radosavljevic@durham.ac.uk [Department of Chemistry, Durham University, South Road, Durham DH1 3LE (United Kingdom)

    2015-02-15

    We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn{sub 2}VO{sub 6}, known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn{sub 2}VO{sub 6} adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO{sub 4} tetrahedra, ZnO{sub 6} octahedra and VO{sub 4} tetrahedra, and Bi{sub 2}O{sub 12} dimers. It is the only known member of the BiM{sub 2}AO{sub 6} (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family which does not appear to be structurally closely related to others. The electronic structure of BiZn{sub 2}VO{sub 6}, calculated by DFT methods, shows that it is an indirect gap semiconductor with a calculated band gap of 1.6 eV, which compares favourably to the experimentally measured value of 2.4 eV. - Graphical abstract: The crystal structure of BiZn{sub 2}VO{sub 6}, a new structure type in the BiM{sub 2}AO{sub 6} (M=Mg, Ca, Cd, Cu, Pb, Mn, Zn; A=V, P, As) family. - Highlights: • Structure solution from PXRD data by repeated minimisations from random starting values. • New structure type in the BiM{sub 2}AO{sub 6} (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family. • Electronic structure calculation.

  19. New transition metal oxide fluorides with ReO{sub 3}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Nakhal, Suliman; Lerch, Martin [Technische Universitaet Berlin (Germany). Inst. fuer Chemie

    2016-08-01

    The new niobium oxide fluorides MNbO{sub 2}F{sub 4} [M = (Cr, Fe)], CrNb{sub 2}O{sub 4}F{sub 5}, and Fe{sub 2}Nb{sub 3}O{sub 6}F{sub 9} were prepared by treatment of chromium or iron nitrate with Nb-containing hydrofluoric acid solutions. Crystal structures were investigated by means of X-ray powder diffraction. All new compounds can be structurally refined in the cubic ReO{sub 3}-type. The iron niobium oxide fluorides are reddish orange, and chromium containing phases exhibit a light green color. The niobium atoms are in the highest formal oxidation state.

  20. Microstructural evolution and creep behaviour of the modified 9% Cr steel with boron and cobalt

    International Nuclear Information System (INIS)

    Nowakowski, P.; Spiradek-Hahn, K.; Brabetz, M.; Zeiler, G.

    1998-01-01

    In the present study the microstructural evolution of the new 9% Cr with boron and cobalt is shown during creep at 650 o C. The minimum creep rates of the new alloy are significantly lower than those of conventional 12 % Cr steel. This is due to the high stability of M 23 C 6 precipitates with respect to the coarsening and the preservation of high dislocation density in the course of creep exposure. (author)

  1. Crystal and magnetic structures of Cr{sub 1∕3}NbSe{sub 2} from neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gubkin, A. F., E-mail: agubkin@imp.uran.ru; Baranov, N. V. [M.N. Miheev Institute of Metal Physics, Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Yekaterinburg (Russian Federation); Proskurina, E. P.; Sherokalova, E. M.; Selezneva, N. V. [Institute of Natural Sciences, Ural Federal University, 620083 Yekaterinburg (Russian Federation); Kousaka, Y.; Akimitsu, J. [Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Miao, P.; Lee, S.; Ishikawa, Y.; Torii, S. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); Zhang, J. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, Guangdong (China); Kamiyama, T. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); Sokendai (Graduate University for Advanced Studies), KEK, Tokai, Ibaragi 319-1106 (Japan); Campo, J. [Aragón Materials Science Institute (CSIC - University of Zaragoza), 50009 Zaragoza (Spain)

    2016-01-07

    Neutron diffraction measurements of the Cr intercalated niobium diselenide Cr{sub 1∕3}NbSe{sub 2} together with magnetization measurements have revealed that this compound exhibits ferromagnetic ordering below T{sub C} = 96 K unlike a chiral helimagnetic order observed in the sulfide compound Cr{sub 1∕3}NbS{sub 2}. As derived from neutron diffraction data, the Cr magnetic moments μ{sub Cr} = 2.83 ± 0.03 μ{sub B} in Cr{sub 1∕3}NbSe{sub 2} are aligned within basal plane. The discrepancy in the magnetic states of Cr{sub 1∕3}NbS{sub 2} and Cr{sub 1∕3}NbSe{sub 2} is ascribed to the difference in the preferential site occupation of Cr ions in crystal lattices. In Cr{sub 1∕3}NbSe{sub 2}, the Cr ions are predominantly distributed over 2b Wyckoff site, which determines a centrosymmetric character of the crystal structure unlike Cr{sub 1∕3}NbS{sub 2}, where the Cr ions are mainly located in 2c position and the crystal structure is non-centrosymmetric.

  2. Electrooxidation of Cr/sup 3+/ at C/PbO/sub 2/

    International Nuclear Information System (INIS)

    Haque, I.U.; Khan, A.; Anwar, S.

    2006-01-01

    Pure and Cu/sup +2/-doped lead dioxide electrodes were prepared by electrodeposition of lead dioxide on carbon-based substrates using lead(II) nitrate bath at 1.5-1.75 V, pH 4-4,5, temperature 60-70 C, and current density 0.0125-0.0175 A/cm/sup 2/. Electrolyses of Cr/sup 3+/ solutions both in divided and undivided cells were used to investigate the electrocatalytic activity. Adhesion and stability of lead dioxide electrodes. Which can serve as industrial electrodes. UV-visible spectrophotometry was used for estimating conversion of Cr/sup 3+/ to Cr/sup 6+/. The electrocatalytic activity of lead dioxide was increased by the doping of copper (II) ions. (author)

  3. Effect of Heat Treatment on the Microstructure and Hardness of 17Cr-0.17N-0.43C-1.7 Mo Martensitic Stainless Steel

    Science.gov (United States)

    Krishna, S. Chenna; Gangwar, Narendra Kumar; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-04-01

    The microstructure and hardness of a nitrogen-containing martensitic stainless steel were investigated as a function of heat treatment using optical microscopy, electron microscopy, amount of retained austenite, and hardness measurement. The steel was subjected to three heat treatments: hardening, cryo treatment, and tempering. The hardness of the steel in different heat-treated conditions ranged within 446-620 HV. The constituents of microstructure in hardened condition were lath martensite, retained austenite, M23C6, M7C3, MC carbides, and M(C,N) carbonitrides. Upon tempering at 500 °C, two new phases have precipitated: fine spherical Mo2C carbides and needle-shaped Cr2N particles.

  4. Microstructure and wear behaviors of laser clad NiCr/Cr3C2-WS2 high temperature self-lubricating wear-resistant composite coating

    Science.gov (United States)

    Yang, Mao-Sheng; Liu, Xiu-Bo; Fan, Ji-Wei; He, Xiang-Ming; Shi, Shi-Hong; Fu, Ge-Yan; Wang, Ming-Di; Chen, Shu-Fa

    2012-02-01

    The high temperature self-lubricating wear-resistant NiCr/Cr3C2-30%WS2 coating and wear-resistant NiCr/Cr3C2 coating were fabricated on 0Cr18Ni9 austenitic stainless steel by laser cladding. Phase constitutions and microstructures were investigated, and the tribological properties were evaluated using a ball-on-disc wear tester under dry sliding condition at room-temperature (17 °C), 300 °C and 600 °C, respectively. Results indicated that the laser clad NiCr/Cr3C2 coating consisted of Cr7C3 primary phase and γ-(Fe,Ni)/Cr7C3 eutectic colony, while the coating added with WS2 was mainly composed of Cr7C3 and (Cr,W)C carbides, with the lubricating WS2 and CrS sulfides as the minor phases. The wear tests showed that the friction coefficients of two coatings both decrease with the increasing temperature, while the both wear rates increase. The friction coefficient of laser clad NiCr/Cr3C2-30%WS2 is lower than the coating without WS2 whatever at room-temperature, 300 °C, 600 °C, but its wear rate is only lower at 300 °C. It is considered that the laser clad NiCr/Cr3C2-30%WS2 composite coating has good combination of anti-wear and friction-reducing capabilities at room-temperature up to 300 °C.

  5. The solvent at antigen-binding site regulated C3d-CR2 interactions through the C-terminal tail of C3d at different ion strengths: insights from molecular dynamics simulation.

    Science.gov (United States)

    Zhang, Yan; Guo, Jingjing; Li, Lanlan; Liu, Xuewei; Yao, Xiaojun; Liu, Huanxiang

    2016-10-01

    The interactions of complement receptor 2 (CR2) and the degradation fragment C3d of complement component C3 play important links between the innate and adaptive immune systems. Due to the importance of C3d-CR2 interaction in the design of vaccines and inhibitors, a number of studies have been performed to investigate C3d-CR2 interaction. Many studies have indicated C3d-CR2 interactions are ionic strength-dependent. To investigate the molecular mechanism of C3d-CR2 interaction and the origin of effects of ionic strength, molecular dynamics simulations for C3d-CR2 complex together with the energetic and structural analysis were performed. Our results revealed the increased interactions between charged protein and ions weaken C3d-CR2 association, as ionic strengths increase. Moreover, ion strengths have similar effects on antigen-binding site and CR2 binding site. Meanwhile, Ala17 and Gln20 will transform between the activated and non-activated states mediated by His133 and Glu135 at different ion strengths. Our results reveal the origins of the effects of ionic strengths on C3d-CR2 interactions are due to the changes of water, ion occupancies and distributions. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Electronic structure and magnetic ordering of the semiconducting chromium trihalides CrCl3, CrBr3, and CrI3

    KAUST Repository

    Wang, Hao

    2011-03-01

    We present results from an electronic structure investigation of the chromium halides CrCl3, CrBr3, and CrI3, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling within the halide-Cr-halide triple layers, our emphasis is on differences in the interlayer magnetic coupling. In agreement with experimental results, our calculations indicate ferromagnetic ordering for CrBr3 as well as CrI3. The antiferromagnetic state of CrCl3 can be reproduced by introducing an on-site electron-electron repulsion. However, we observe that the ground state depends critically on the specific approach used. Our results show that a low temperature structural phase transition from monoclinic to trigonal is energetically favourable for CrCl3. © 2011 IOP Publishing Ltd.

  7. Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

    Science.gov (United States)

    Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

    2018-06-01

    Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

  8. Ferromagnetic-phase transition in the spinel-type CuCr2Te4

    International Nuclear Information System (INIS)

    Suzuyama, Takeshi; Awaka, Junji; Yamamoto, Hiroki; Ebisu, Shuji; Ito, Masakazu; Suzuki, Takashi; Nakama, Takao; Yagasaki, Katsuma; Nagata, Shoichi

    2006-01-01

    Ferromagnetic-phase transition in spinel-type CuCr 2 Te 4 has been clearly observed. CuCr 2 Te 4 is a telluride-spinel with the lattice constant a=11.134A, which has been synthesized successfully. The heat capacity exhibits a sharp peak due to the ferromagnetic-phase transition with the Curie temperature T C =326K. This value of T C corresponds exactly to that of the negative peak of dM/dT in low field of 1.0Oe. The magnetic susceptibility shows the Curie-Weiss behavior between 380 and 650K with the effective magnetic moment μ eff =4.14μ B /Cr-ion and the Weiss constant θ=+357K. The low temperature magnetization indicates the spin-wave excitations, where the existence of first term of Bloch T 3/2 law and the next T 5/2 term are verified experimentally. This spin-wave excitation is detected up to approximately 250K which is a fairly high temperature

  9. Structural evolution of Fe-18Ni-16Cr-4Al steel during aging at 950 .deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Man; Jang, Jinsung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Zhou, Zhangjian [School of Materials Science and Engineering, USTB, Beijing (China)

    2015-05-15

    Austenitic stainless steels are also among important structural materials for in-core components of nuclear reactors, and the performance, the oxidation resistance as well as the mechanical strength at high temperature are further expected after Fukushima accident. Alumina-forming austenitic (AFA) steel was first developed by Y. Yamamoto et al. , which showed a good combination of oxidation resistance and creep resistance. The strengthening is achieved through nano-sized MX and Laves. Microstructural evolution of Fe-18Ni-16Cr-4Al during aging at 950 .deg. C was studied. This steel consists of two phases of austenite and ferrite. During aging, needle-shaped NiAl precipitates in austenite, while round shaped NiAl form in ferrite, which is supposed to be due to different crystal structural parameters.

  10. Structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the quaternary Heusler compound FeCrRuSi: A first-principles study.

    Science.gov (United States)

    Wang, Xiaotian; Khachai, Houari; Khenata, Rabah; Yuan, Hongkuan; Wang, Liying; Wang, Wenhong; Bouhemadou, Abdelmadjid; Hao, Liyu; Dai, Xuefang; Guo, Ruikang; Liu, Guodong; Cheng, Zhenxiang

    2017-11-23

    In this paper, we have investigated the structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the equiatomic quaternary Heusler (EQH) compound FeCrRuSi using the density functional theory (DFT) and the quasi-harmonic Debye model. Our results reveal that FeCrRuSi is a half-metallic material (HMM) with a total magnetic moment of 2.0 μ B in agreement with the well-known Slater-Pauling rule M t  = Z t  - 24. Furthermore, the origin of the half-metallic band gap in FeCrRuSi is well studied through a schematic diagram of the possible d-d hybridization between Fe, Cr and Ru elements. The half-metallic behavior of FeCrRuSi can be maintained in a relatively wide range of variations of the lattice constant (5.5-5.8 Å) under uniform strain and the c/a ratio (0.96-1.05) under tetragonal distortion. The calculated phonon dispersion, cohesive and formation energies, and mechanical properties reveal that FeCrRuSi is stable with an EQH structure. Importantly, the compound of interest has been prepared and is found to exist in an EQH type structure with the presence of some B2 disorder. Moreover, the thermodynamic properties, such as the thermal expansion coefficient α, the heat capacity C V , the Grüneisen constant γ, and the Debye temperature Θ D are calculated.

  11. Electron pairing analysis of the Fischer-type chromium-carbene complexes (CO){sub 5}Cr=C(X)R (X=H, OH, OCH{sub 3}, NH{sub 2}, NHCH{sub 3} and R=H, CH{sub 3}, CH=CH{sub 2}, Ph, C-CH )

    Energy Technology Data Exchange (ETDEWEB)

    Poater, Jordi; Cases, Montserrat; Fradera, Xavier; Duran, Miquel; Sola, Miquel

    2003-10-15

    The electron-pair density distributions of a series of 25 Fischer carbene complexes of the type (CO){sub 5}Cr=C(X)R (X=H, OH, OCH{sub 3}, NH{sub 2}, NHCH{sub 3} and R=H, CH{sub 3}, CH=CH{sub 2}, Ph, C-CH) are analyzed using the Atoms in Molecules theory. Localization and delocalization indices are used to characterize the electron pairing taking place in the Cr=C---X moiety in these complexes. Electron delocalization between the Cr and C atoms and between the C atom and the X group are related to the {pi}-donor strength of the X group and the degree of back-donation between the chromium pentacarbonyl and the carbene fragments. The results obtained with the Atoms in Molecules theory complement those obtained in a previous study by means of energy and charge decomposition analyses. Electron delocalization between the Cr atom and the X group is consistent with the hypothesis of a weak 3-center 4-electron bonding interaction in the Cr=C-X group of atoms. Except for X=H, {delta}(Cr,X) increases with the decrease of the {pi}-donor character of the X group.

  12. Two structure types based on Si6O15 rings: synthesis and structural and spectroscopic characterisation of Cs1.86K1.14DySi6O15 and Cs1.6K1.4SmSi6O15

    International Nuclear Information System (INIS)

    Wierzbicka-Wieczorek, Maria; Goeckeritz, Martin; Kolitsch, Uwe; Lenz, Christoph; Giester, Gerald

    2015-01-01

    The silicate Cs 1.86 K 1.14 DySi 6 O 15 represents a mixed tetrahedral-octahedral framework structure type based on roughly circular Si 6 O 15 rings and isolated DyO 6 octahedra. The silicate Cs 1.6 K 1.4 SmSi 6 O 15 has a layered atomic arrangement built from corrugated Si 6 O 15 layers containing four-, six- and eight-membered rings. The layers are connected by isolated SmO 6 octahedra to form a mixed tetrahedral-octahedral framework. This structure shows a close structural relationship to β-K 3 NdSi 6 O 15 and a less close one to dehydrated elpidite (Na 2 ZrSi 6 O 15 ). In both structures, Cs/K atoms occupy large voids. The silicates were obtained through high-temperature flux syntheses. Their crystal structures have been determined from single-crystal X-ray diffraction data. Cs 1.86 K 1.14 DySi 6 O 15 crystallises in R32 (no. 155) with a = 13.896(2), c = 35.623(7) Aa and V = 5957.2(17) Aa 3 , whereas Cs 1.6 K 1.4 SmSi 6 O 15 crystallises in Cmca (no. 64) with a = 14.474(3), b = 14.718(3), c = 15.231(3) Aa and V = 3244.7(11) Aa 3 . The Dy 3+ and Sm 3+ cations present in the silicates cause PL emission bands in the visible yellow-to-orange spectral range. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Structure and magnetic properties of (Nd1-xErx)3Fe25Cr4.0 (0 ≤ x ≤ 0.8) compounds

    International Nuclear Information System (INIS)

    Luo Hongzhi; Jia Lin; Li Yangxian; Meng Fanbin; Shen Jiang; Chen Nanxian; Wu Guangheng; Yang Fuming

    2004-01-01

    The structure and magnetic properties of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 compounds with x = 0-0.8 have been investigated using x-ray powder diffraction (XRD) and magnetic measurements. It has been found that all the compounds crystallize in a Nd 3 (Fe,Ti) 29 -type structure. Substitution of Er for Nd leads to a contraction of the unit-cell volume. The Curie temperature, T c , and the saturation magnetization, M s , of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 decrease monotonically with increasing Er content. The easy magnetization direction (EMD) of Nd 3 Fe 25 Cr 4.0 at room temperature is close to the [040] direction but may be a little out of the basal plane. With increasing Er content, the EMD changes closer to the [40-2] direction and the tilt angle increases. Both the XRD patterns and ac susceptibility indicate the appearance of a spin reorientation for x = 0-0.4 as the temperature decreases from room temperature to 77 K. The spin reorientation temperature, T sr , increases monotonically with increasing Er content from 158 K for x = 0 to 198 K for x = 0.4. A first order magnetization process (FOMP) occurs for all the compounds, and the critical field of the FOMP decreases with increasing Er content from 6.6 T for x = 0 to 2.0 T for x = 0.7

  14. Influence of the Cr and Ni concentration in CoCr and CoNi alloys on the structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, E. [Nipson Technology, 12 Avenue des Trois chênes, Techn’Hom 3, Belfort 90000 (France); Liu, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Billard, A. [IRTES-LERMPS EA 7274, UTBM, Site de Montbéliard, Belfort Cedex 90010 (France); Dekens, A. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Perry, F. [PVDco, 30 rue de Badménil, Baccarat 54120 (France); Mangin, S.; Hauet, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France)

    2017-01-15

    The crystalline and magnetic properties of micron thick magnetron sputtered Co{sub 1−x}Cr{sub x} and Co{sub 1−x}Ni{sub x} alloy films are analyzed in the view of their implementation as semi-hard magnets. All of the tested films crystallize in an hcp lattice, at least up to 35 at% of alloying elements (Cr or Ni). The structural study shows that the ratio of hcp phase with [0001] axis orientated perpendicular to the film as compared with in-plane orientation increases (resp. decreases), when Ni (resp. Cr) concentration increases independently of the post-annealing temperature. The orientation of the magnetization results from the competition between the demagnetization field which tends to align the magnetization in plane and the crystalline anisotropy which tends to maintain the magnetization along the [0001] axis. Interestingly, we find that, although Co and Ni are very similar atoms, Co{sub 1−x}Ni{sub x} alloys crystalline anisotropy can be strongly increased and reach up to twice the anisotropy of the best Co{sub 1−x}Cr{sub x} alloy, while maintaining a magnetization at saturation above 1200 kA/m. The thermal stability of the structural and magnetic properties of both alloys is demonstrated for an annealing temperature up to 300 °C. - Highlights: • Sputtered CoCr and CoNi films are analyzed for their semi-hard magnetic properties. • CoNi alloys exhibits higher saturation magnetization and crystalline anisotropy. • These evolutions can be directly correlated to the quality of hcp crystal orientation. • Thermal stability of structural and magnetic properties is demonstrated up to 300 °C.

  15. Effects of W on microstructure of as-cast 28 wt.%Cr–2.6 wt.%C–(0–10)wt.%W irons

    Energy Technology Data Exchange (ETDEWEB)

    Imurai, S. [Department of Physics and Materials Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thanachayanont, C.; Pearce, J.T.H. [National Metal and Materials Technology Center, Pathumthani 12120 (Thailand); Tsuda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Chairuangsri, T., E-mail: tchairuangsri@gmail.com [Department of Industrial Chemistry, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-01-15

    Microstructures of as-cast 28 wt.%Cr–2.6 wt.%C irons containing (0–10)wt.%W with the Cr/C ratio about 10 were studied and related to their hardness. The experimental irons were cast into dry sand molds. Microstructural investigation was performed by light microscopy, X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometry. It was found that the irons with 1 to 10 wt.%W addition was hypereutectic containing large primary M{sub 7}C{sub 3}, whereas the reference iron without W addition was hypoeutectic. The matrix in all irons was austenite, partly transformed to martensite during cooling. The volume fractions of primary M{sub 7}C{sub 3} and the total carbides increased, but that of eutectic carbides decreased with increasing the W content of the irons. W addition promoted the formation of W-rich M{sub 7}C{sub 3}, M{sub 6}C and M{sub 23}C{sub 6}. At about 4 wt.%W, two eutectic carbides including M{sub 7}C{sub 3} and M{sub 6}C were observed together with primary M{sub 7}C{sub 3}. At 10 wt.%W, multiple carbides including primary M{sub 7}C{sub 3}, fish-bone M{sub 23}C{sub 6}, and M{sub 6}C were observed. M{sub x}C where x = 3 or less has not been found due possibly to the high M/C ratio in the studied irons. W distribution to all carbides has been determined increasing from ca. 0.3 to 0.8 in mass fraction as the W content in the irons was increased. W addition led to an increase in Vickers macro-hardness of the irons up to 671 kgf/(mm){sup 2} (HV30/15) obtained from the iron with 10 wt.%W. The formation of primary M{sub 7}C{sub 3} and aggregates of M{sub 6}C and M{sub 23}C{sub 6} were the main reasons for hardness increase, indicating potentially improved wear performance of the as-cast irons with W addition. - Highlights: • W addition at 1 up to 10 wt.%W to Fe–28Cr–2.6C produced “hypereutectic” structure. • W addition promoted the formation of W-rich M{sub 7}C{sub 3}, M{sub 6}C and M

  16. Mol 7C/6; Mol 7C/6

    Energy Technology Data Exchange (ETDEWEB)

    Aberle, J.; Schleisiek, K.; Schmuck, I.; Schmidt, L.; Romer, O.; Weih, G.

    1995-08-01

    The Mol 7C/6 coolant blockage experiment in the Belgian BR2 reactor yielded results different from Mol 7C experiments with low burnup pins: At 10% burnup local failure is not self-limiting, but requires active systems for detection and scram. The Mol 7C series was finished in 1991. In each of the test bundles Mol 7C/4, /5 and /6, 30 Mk I pins pre-irradiated in KNK II were used. The central blockage consisted of enriched UO{sub 2} covering 30 percent of the bundle cross-section, with a height of 40 mm. The most important system for timely detection of coolant blockages of the type studied in Mol 7C/6 is based on DND. (orig.)

  17. Microscale fracture mechanisms of a Cr{sub 3}C{sub 2}-NiCr HVOF coating

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Andrew L., E-mail: Andrew.robertson99987@gmail.com; White, Ken W.

    2017-03-14

    Thermal spray coatings, often composed of heterogeneous, multiphase microstructures, may, consequently, exhibit complex fracture behavior. For such coating structures, conventional mechanical evaluation methods fail to isolate the contribution of microstructural features to the overall fracture behavior. For this reason, this study employed focused ion beam machined (FIB) microcantilever beams and FIB sectioning methods to study the fracture mechanisms important at the scale of the heterogeneous Cr{sub 3}C{sub 2}-NiCr thermal spray coating. We found three fracture modes, namely, intergranular matrix fracture, matrix/carbide interfacial fracture, and carbide cleavage. By comparison, microindentation-induced cracks, the frequency of crack deflection around carbides is significantly more prevalent at this much larger crack dimension. This mechanistic variation provides some insight into the specific role and limitations of the microcantilever beam technique for fracture characterization of composite microstructures.

  18. Comparison of Glomerular Filtration Rate Estimation from Serum Creatinine and Cystatin C in HNF1A-MODY and Other Types of Diabetes

    Directory of Open Access Journals (Sweden)

    Magdalena Szopa

    2015-01-01

    Full Text Available Introduction. We previously showed that in HNF1A-MODY the cystatin C-based glomerular filtration rate (GFR estimate is higher than the creatinine-based estimate. Currently, we aimed to replicate this finding and verify its clinical significance. Methods. The study included 72 patients with HNF1A-MODY, 72 with GCK-MODY, 53 with type 1 diabetes (T1DM, 70 with type 2 diabetes (T2DM, and 65 controls. Serum creatinine and cystatin C levels were measured. GFR was calculated from creatinine and cystatin C using the CKD-EPI creatinine equation (eGRF-cr and CKD-EPI cystatin C equation (eGFR-cys, respectively. Results. Cystatin C levels were lower (p<0.001 in the control (0.70±0.13 mg/L, HNF1A (0.75±0.21, and GCK (0.72±0.16 mg/L groups in comparison to those with either T1DM (0.87±0.15 mg/L or T2DM (0.9±0.23 mg/L. Moreover, eGFR-cys was higher than eGRF-cr in HNF1A-MODY, GCK-MODY, and the controls (p=0.004; p=0.003; p<0.0001. This corresponded to 8.9 mL/min/1.73 m2, 9.7 mL/min/1.73 m2, and 16.9 mL/min/1.73 m2 of difference. Additionally, T1DM patients had higher eGFR-cr than eGFR-cys (11.6 mL/min/1.73 m2; p=0.0004; no difference occurred in T2DM (p=0.91. Conclusions. We confirmed that eGFR-cys values in HNF1A-MODY patients are higher compared to eGFR-cr. Some other differences were also described in diabetic groups. However, none of them appears to be clinically relevant.

  19. Crystal structure of the HA3 subcomponent of Clostridium botulinum type C progenitor toxin.

    Science.gov (United States)

    Nakamura, Toshio; Kotani, Mao; Tonozuka, Takashi; Ide, Azusa; Oguma, Keiji; Nishikawa, Atsushi

    2009-01-30

    The Clostridium botulinum type C 16S progenitor toxin contains a neurotoxin and several nontoxic components, designated nontoxic nonhemagglutinin (HA), HA1 (HA-33), HA2 (HA-17), HA3a (HA-22-23), and HA3b (HA-53). The HA3b subcomponent seems to play an important role cooperatively with HA1 in the internalization of the toxin by gastrointestinal epithelial cells via binding of these subcomponents to specific oligosaccharides. In this study, we investigated the sugar-binding specificity of the HA3b subcomponent using recombinant protein fused to glutathione S-transferase and determined the three-dimensional structure of the HA3a-HA3b complex based on X-ray crystallography. The crystal structure was determined at a resolution of 2.6 A. HA3b contains three domains, domains I to III, and the structure of domain I resembles HA3a. In crystal packing, three HA3a-HA3b molecules are assembled to form a three-leaved propeller-like structure. The three HA3b domain I and three HA3a alternate, forming a trimer of dimers. In a database search, no proteins with high structural homology to any of the domains (Z score >10) were found. Especially, HA3a and HA3b domain I, mainly composed of beta-sheets, reveal a unique fold. In binding assays, HA3b bound sialic acid with high affinity, but did not bind galactose, N-acetylgalactosamine, or N-acetylglucosamine. The electron density of liganded N-acetylneuraminic acid was determined by crystal soaking. In the sugar-complex structure, the N-acetylneuraminic acid-binding site was located in the cleft formed between domains II and III of HA3b. This report provides the first determination of the three-dimensional structure of the HA3a-HA3b complex and its sialic acid binding site. Our results will provide useful information for elucidating the mechanism of assembly of the C16S toxin and for understanding the interactions with oligosaccharides on epithelial cells and internalization of the botulinum toxin complex.

  20. Erosion-oxidation behavior of thermal sprayed Ni20Cr alloy and WC and Cr3C2 cermet coatings

    Directory of Open Access Journals (Sweden)

    Clarice Terui Kunioshi

    2005-06-01

    Full Text Available An apparatus to conduct high temperature erosion-oxidation studies up to 850 °C and with particle impact velocities up to 15 m.s-1 was designed and constructed in the Corrosion Laboratories of IPEN. The erosion-oxidation behavior of high velocity oxy fuel (HVOF sprayed alloy and cermet coatings of Ni20Cr, WC 20Cr7Ni and Cr3C2 Ni20Cr on a steel substrate has been studied. Details of this apparatus and the erosion-oxidation behavior of these coatings are presented and discussed. The erosion-oxidation behavior of HVOF coated Cr3C2 25(Ni20Cr was better than that of WC 20Cr7Ni, and the erosion-oxidation regimes have been identified for these coatings at particle impact velocity of 3.5 m.s-1, impact angle of 90° and temperatures in the range 500 to 850 °C.

  1. Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) with Th{sub 7}Fe{sub 3}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Misse, Patrick R.N.; Mbarki, Mohammed [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany); Fokwa, Boniface P.T., E-mail: boniface.fokwa@ac.rwth-aachen.de [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany)

    2012-08-15

    Powder samples and single crystals of the new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. - Graphical abstract: The new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) has been synthesized by arc melting the elements under purified argon atmosphere. Beside the 3d/4d site preference within the whole solid solution, an unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. Highlights: Black-Right-Pointing-Pointer Synthesis of a new boride series fulfilling Vegard Acute-Accent s rule. Black-Right-Pointing-Pointer 3d/4d site preference. Black-Right-Pointing-Pointer Unexpected Ru/Rh site preference. Black-Right-Pointing-Pointer Rh-rich region is Pauli paramagnetic. Black-Right-Pointing-Pointer Ru-rich region is Pauli and temperature-dependent paramagnetic.

  2. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    Energy Technology Data Exchange (ETDEWEB)

    Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)] [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Inden, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)

    2010-10-15

    The growth kinetics of Laves phase precipitates (type Fe{sub 2}W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M{sub 23}C{sub 6} and the Laves phase showed that M{sub 23}C{sub 6} carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  3. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    International Nuclear Information System (INIS)

    Prat, O.; Garcia, J.; Rojas, D.; Carrasco, C.; Inden, G.

    2010-01-01

    The growth kinetics of Laves phase precipitates (type Fe 2 W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M 23 C 6 and the Laves phase showed that M 23 C 6 carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  4. (E-3-Methyl-6-(3-oxo-3-(3,4,5-trimethoxyphenylprop-1-en-1-yl-2(3H-benzothiazolone

    Directory of Open Access Journals (Sweden)

    Yordanka Ivanova

    2016-09-01

    Full Text Available The title compound, (E-3-methyl-6-(3-oxo-3-(3,4,5-trimethoxyphenylprop-1-en-1-yl-2(3H-benzothiazolone, was synthesized by both an acid- and base-catalyzed aldol condensation of 3-methyl-6-acetyl-2(3H-benzothiazolone and 3,4,5-trimethoxyacetophenone. The structure of the target compound was confirmed using 1H-NMR, 13C-NMR, IR, MS, and elemental analysis.

  5. Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=–F, –Cl, –Br, –CH{sub 3}, –C{sub 6}H{sub 4}, –F{sub 2}, –(CH{sub 3}){sub 2}) materials

    Energy Technology Data Exchange (ETDEWEB)

    Buragohain, Amlan [Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam (India); Couck, Sarah [Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); Van Der Voort, Pascal [Department of Inorganic and Physical Chemistry, Ghent University, COMOC – Center for Ordered Materials, Organometallics and Catalysis, Krijgslaan 281-S3, 9000 Ghent (Belgium); Denayer, Joeri F.M. [Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); Biswas, Shyam, E-mail: sbiswas@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam (India)

    2016-06-15

    Four existing and three new functionalized chromium terephthalates having MIL-101 topology and denoted as Cr-MIL-101-X (existing ones with X=–F, 1-F; –Cl, 2-Cl; –Br, 3-Br; –CH{sub 3}, 4-CH{sub 3}; new ones with X=–C{sub 6}H{sub 4}, 5-C{sub 6}H{sub 4}; –F{sub 2}, 6-F{sub 2}, –(CH{sub 3}){sub 2}, 7-(CH{sub 3}){sub 2}) were synthesized under hydrothermal conditions. All the materials except 5-C{sub 6}H{sub 4} could be prepared by a general synthetic route, in which the mixtures of CrO{sub 3}, H{sub 2}BDC-X (BDC=1,4-benzenedicarboxylate) linkers, conc. HCl and water with a molar ratio of 1:1:3.9:222.2 were reacted at 180 °C for 144 h. Compared to the 144 h of synthesis time, three of the compounds, namely 1-Cl, 2-Br and 5-C{sub 6}H{sub 4}, could be prepared in much shorter reaction times (12–18 h at 180–210 °C). The materials possess high thermal stability up to 270–300 °C in an air atmosphere. The activated compounds exhibit significant porosity (S{sub BET} range: 1273–2135 m{sup 2} g{sup −1}). At 0 °C and 1 bar, the CO{sub 2} adsorption capacities of the compounds fall in the 1.7–2.9 mmol g{sup −1} range. Compounds 1-F and 6-F{sub 2} showed enhanced CO{sub 2} uptake values compared to parent Cr-MIL-101. The benzene adsorption capacities of the compounds lie in the range of 66.2–139.5 molecules per unit cell at 50 °C and p/p{sub 0}=0.35. The increased benzene uptake value of 1-F compared to un-functionalized Cr-MIL-101 and 4-CH{sub 3} suggests that the fluorination has induced more hydrophobicity in Cr-MIL-101 as compared to the methylation. - Graphical abstract: Benzene adsorption by seven functionalized Cr-MIL-101-X metal-organic framework (MOF) materials Display Omitted - Highlights: • Seven functionalized Cr-MIL-101-X materials were synthesized solvothermally. • All Cr-MIL-101-X materials exhibited high thermal stability up to 270–300 °C in air. • All Cr-MIL-101-X compounds displayed considerable porosity towards N{sub 2

  6. Structure elucidation of 3-[1-(6-methoxy-2-naphtyl)ethyl]-6-(2,4-dichlorophenyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine, C23H18Cl2N4OS from synchrotron X-ray powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gündoğdu, Gülsüm; Aytaç, Sevim Peri; Müller, Melanie; Tozkoparan, Birsen; Kaynak, Filiz Betül

    2017-12-01

    The 3-[1-(6-methoxy-2-naphtyl)ethyl]-6-(2,4-dichlorophenyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine, C23H18Cl2N4OS compound was synthesized, as a member of the family of novel potential anticancer agents. The structure of the title compound was characterized by IR,1H-NMR, mass spectroscopy, and elemental analysis, previously. In this study, the crystal structure of this compound has been determined from synchrotron X-ray powder diffraction data. The crystal structure was solved by simulated annealing and the final structure was achieved by Rietveld refinement method using soft restrains on all interatomic bond lengths and angles. This compound crystallizes in space groupP21,Z= 2, with the unit-cell parametersa= 15.55645(11) Å,b= 8.61693(6) Å,c= 8.56702(6) Å,β= 104.3270(4)°, andV= 1112.68(1) Å3. In the crystal structure, strong C-H∙∙∙πand weak intermolecular hydrogen-bonding interactions link the molecules into a three-dimensional network. The molecules are in a head-to-head arrangement in the unit cell.

  7. Structural relaxation and colour in the spinel-magnesiochromite (MgAl2O4-MgCr2O4) and gahnite-zincochromite (ZnAl2O4-ZnCr2O4) solid solution series

    Science.gov (United States)

    Hålenius, U.; Andreozzi, G. B.; Skogby, H.

    2009-04-01

    Recent studies on binary mineral solid solution series utilising synchrotron based x-ray absorption spectroscopies have indicated strong structural relaxation. For instance, it has been suggested that the real Cr-O bond distances remain nearly constant (relaxation parameter (ɛ) of 0.85, where ɛ=1 equals full relaxation) over the entire compositional range of the MgAl2O4-MgCr2O4 series (Juhin et al. 2007). In the present study we have measured room temperature optical absorption spectra of synthetic single crystals of the ZnAl2-2xCr2xO4 (0.03?x?1) and MgAl2-2xCr2xO4(0.02?x?1) series with the aim to explore the real architecture of the structure and in particular the Cr-O distance as function of composition. Our crystals were synthesized by means of flux-growth methods under atmospheric pressure and temperature profiles resulting in an estimated cation ordering temperature of ca 850 °C. Crystals close to the spinel (sensu stricto) and gahnite end-member compositions were faintly red in colour. With increasing Cr-content the crystals become more intensely red-coloured and at the higher Cr-contents there is a distinct shift towards a dark greenish colouration. These colour changes are reflected in the measured optical spectra by the position and intensity of the two spin-allowed electronic d-d transitions in octahedrally coordinated Cr3+ at ca 18000 (4A2g -4T2g (4F) transition) and 25000 cm-1(4A2g -4T1g (4F) transition). The energy of the first transition (?1-band) is ca 1200 cm-1 lower in magnesiochromite than in weakly Cr-doped spinel (x=0.02) and ca 1400 cm-1 lower in zincochromite than in gahnite with the lowest Cr-content (x=0.03). Concomitantly the energy of the second transition (?2-band) decreases with increasing Cr-content in both series by ca. 1800 cm-1. From the position of the ?1-band, a decrease in crystal field splitting, 10Dq, for six-coordinated Cr3+ with increasing Cr-content in the MgAl2-2xCr2xO4 and ZnAl2-2xCr2xO4 series of 6.5 and 7

  8. Synthesis and structural characterization of Al4SiC4-homeotypic aluminum silicon oxycarbide, [Al4.4Si0.6][O1.0C2.0]C

    International Nuclear Information System (INIS)

    Kaga, Motoaki; Iwata, Tomoyuki; Nakano, Hiromi; Fukuda, Koichiro

    2010-01-01

    A new quaternary layered oxycarbide, [Al 4.39(5) Si 0.61(5) ] Σ5 [O 1.00(2) C 2.00(2) ] Σ3 C, has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The title compound was found to be hexagonal with space group P6 3 /mmc, Z=2, and unit-cell dimensions a=0.32783(1) nm, c=2.16674(7) nm and V=0.20167(1) nm 3 . The atom ratios Al:Si were determined by EDX, and the initial structural model was derived by the direct methods. The final structural model showed the positional disordering of one of the three types of Al/Si sites. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R wp =3.73% (S=1.20), R p =2.94%, R B =1.04% and R F =0.81%. The crystal was an inversion twin. Each twin-related individual was isostructural with Al 4 SiC 4 (space group P6 3 mc, Z=2). - Graphical abstract: A new oxycarbide discovered in the Al-Si-O-C system, Al 4 SiC 4 -homeotypic [Al 4.4 Si 0.6 ][O 1.0 C 2.0 ]C. The crystal is an inversion twin, and hence the structure is represented by a split-atom model. The three-dimensional electron density distributions are determined by the maximum-entropy methods-based pattern fitting, being consistent with the disordered structural model.

  9. Chemical & Material Risk Management Initiatives: Reach & Cr6+ Strategies (Briefing Charts)

    Science.gov (United States)

    2011-02-01

    Definition Acquisition, Technology and Logistics 17 DoD Hexavalent Chromium Minimization Strategy Non‐ Chrome  Primer Acquisition, Technology and...Logistics 18 Hexavalent Chromium (Cr6+) - Some Facts • Cr6+ compounds are wonderful corrosion inhibitors • Cr6+ compounds are highly toxic – We’ve learned...and Logistics 21 DoD Hexavalent Chromium Minimization Policy Acquisition, Technology and Logistics 22 Myth-busters • The DoD policy does not ban the

  10. NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Jumpei, E-mail: higuchi@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Sato, Yoichi [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2011-09-30

    NiFe epitaxial films are prepared on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

  11. NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

    International Nuclear Information System (INIS)

    Higuchi, Jumpei; Ohtake, Mitsuru; Sato, Yoichi; Kirino, Fumiyoshi; Futamoto, Masaaki

    2011-01-01

    NiFe epitaxial films are prepared on Cr(211) bcc and Cr(100) bcc underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211) bcc and Cr(100) bcc underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

  12. Structural, magnetic, and dielectric properties of multiferroic Co1-xMgxCr2O4 nanoparticles

    Science.gov (United States)

    Kamran, M.; Ullah, A.; Rahman, S.; Tahir, A.; Nadeem, K.; Anis ur Rehman, M.; Hussain, S.

    2017-07-01

    We examined the structural, magnetic, and dielectric properties of Co1-xMgxCr2O4 nanoparticles with composition x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1 in detail. X-ray diffraction (XRD) revealed normal spinel structure for all the samples. Rietveld refinement fitting results of the XRD showed no impurity phases which signifies the formation of single phase Co1-xMgxCr2O4 nanoparticles. The average crystallite size showed a peak behaviour with maxima at x = 0.6. Raman and Fourier transform infrared (FTIR) spectroscopy also confirmed the formation of single phase normal spinel for all the samples and exhibited dominant vibrational changes for x ≥ 0.6. For x = 0 (CoCr2O4), zero field cooled/field cooled (ZFC/FC) magnetization curves showed paramagnetic (PM) to ferrimagnetic (FiM) transition at Tc = 97 K and a conical spiral magnetic order at Ts = 30 K. The end members CoCr2O4 (x = 0) and MgCr2O4 (x = 1) are FiM and antiferromagnetic (AFM), respectively. Tc and Ts showed decreasing trend with increasing x, followed by an additional AFM transition at TN = 15 K for x = 0.6. The system finally stabilized and changed to highly frustrated AFM structure at x = 1 due to formation of pure MgCr2O4. High field FC curves (5T) depicted nearly no effect on spiral magnetic state, which is attributed to strong exchange B-B magnetic interactions at low temperatures. Dielectric parameters showed a non-monotonous behaviour with Mg concentration and were explained with the help of Maxwell-Wagner model and Koop's theory. Dielectric properties were improved for nanoparticles with x = 0.6 and is attributed to their larger average crystallite size. In summary, Mg doping has significantly affects the structural, magnetic, and dielectric properties of CoCr2O4 nanoparticles, which can be attributed to variations in local magnetic exchange interactions and variation in average crystallite size of these chromite nanoparticles.

  13. Microstructure evolution and mechanical properties of X12CrMoWVNbN10-1-1 steel during quenching and tempering process

    Directory of Open Access Journals (Sweden)

    Xingang Tao

    2016-01-01

    Full Text Available The effect of heat treatments was investigated on the microstructure evolution and mechanical properties of X12CrMoWVNbN10-1-1 steel. The as-received steel was austenitized at 1080 °C for 16 h and cooled in furnace, following tempered in two steps, i.e. at 570 °C for 18 h and then at 690 °C for 24 h. The austenitized sample had a typical lath martensite structure with some retained austenite and no delta ferrite was observed after austenitization. After the first tempering at 570 °C, there was no retained austenite remained but it resulted in the forming of precipitates, such as Cr-rich M7C3, Cr-rich M23C6, Cr-rich M2N, Nb-rich MN, and the subgrain, as well as the reduction in dislocation density. However, microstructure observation after secondary tempering proved the further arrangement of dislocation, subgrain growth and the coarsening of precipitates. Hardness and impact tests were carried out for establishing a correlation between microstructure and mechanical properties. Finally, a careful fractographic analysis of impact samples had been done using SEM and EDS.

  14. Submerged Arc Stainless Steel Strip Cladding—Effect of Post-Weld Heat Treatment on Thermal Fatigue Resistance

    Science.gov (United States)

    Kuo, I. C.; Chou, C. P.; Tseng, C. F.; Lee, I. K.

    2009-03-01

    Two types of martensitic stainless steel strips, PFB-132 and PFB-131S, were deposited on SS41 carbon steel substrate by a three-pass submerged arc cladding process. The effects of post-weld heat treatment (PWHT) on thermal fatigue resistance and hardness were evaluated by thermal fatigue and hardness testing, respectively. The weld metal microstructure was investigated by utilizing optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results showed that, by increasing the PWHT temperature, hardness decreased but there was a simultaneous improvement in weldment thermal fatigue resistance. During tempering, carbide, such as (Fe, Cr)23C6, precipitated in the weld metals and molybdenum appeared to promote (Fe, Cr, Mo)23C6 formation. The precipitates of (Fe, Cr, Mo)23C6 revealed a face-centered cubic (FCC) structure with fine grains distributed in the microstructure, thereby effectively increasing thermal fatigue resistance. However, by adding nickel, the AC1 temperature decreased, causing a negative effect on thermal fatigue resistance.

  15. Microstructure and Wear Resistance of TiC Composite Coating in situ Synthesized on 35CrMnSi Steel by Argon Arc Cladding%35CrMnSi 表面氩弧熔覆原位自生 TiC 复合涂层的组织及耐磨性

    Institute of Scientific and Technical Information of China (English)

    丁天; 孟君晟; 乔盛楠; 吕东亮; 宋永平; 李阳

    2014-01-01

    Objective To improve the wear resistance of cutting tooth and to prolong its service life. Methods The TiC enhanced nickel-based composite coating was prepared on the surface of 35CrMnSi steel by argon arc cladding technique. The microstructure of the coating was analyzed by OM, SEM and XRD. Microhardness and wear resistance at room temperature of the composite coat-ing were examined by means of microhardness testing and impact abrasion resistance testing, respectively. Results The compact microstructure was obtained in the composite coating, and good metallurgical bonding could be obtained between the 35CrMnSi steel and cladding coating, with the main phases of TiC, γ-Ni and M23 C6 . The majority of TiC was blocky. The TiC particles was about 1 ~ 2 μm in size and the particles were dispersed in the coatings. The hardness and wear resistance of the coating were related with the (Ti+C) content. The highest hardness of 20% (Ti+C) coating was 1190HV. The relative wear resistance of the composite coating was 7. 5 times higher than that of 35CrMnSi steel. Conclusion The cladding coating reinforced by TiC particle showed ap-parently improved surface hardness as compared to 35CrMnSi steel. The wear mechanism of the composite coating under impact loading at room temperature was micro-cutting wear. The wear resistance of coating was greatly increased by argon arc cladding.%目的:提高截齿的耐磨性,延长其使用寿命。方法利用氩弧熔覆技术在35CrMnSi 钢表面制备 TiC 增强镍基复合涂层,分析涂层的显微组织和物相组成,测试涂层在室温下的显微硬度和耐磨性,并分析磨损机制。结果氩弧熔覆涂层的显微组织致密均匀,涂层与基体呈冶金结合,主要由 TiC,γ-Ni, M23 C6等物相组成。 TiC 颗粒呈块状,尺寸为1~2μm,弥散分布在涂层中。涂层硬度和耐磨性与(Ti+C)含量有关,熔覆粉末中(Ti+C)质量分数为20%时,涂层最高硬度可达1190HV,耐磨性达到基体的7.5

  16. Microstructural characterization of Y{sub 2}O{sub 3} ODS-Fe-Cr model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Castro, V. de [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)], E-mail: vanessa.decastro@materials.ox.ac.uk; Leguey, T.; Munoz, A.; Monge, M.A.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Marquis, E.A.; Lozano-Perez, S.; Jenkins, M.L. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)

    2009-04-30

    Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y{sub 2}O{sub 3} and the other Y{sub 2}O{sub 3}-free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes <10 nm were also observed. Both alloys also contained M{sub 3}C and M{sub 23}C{sub 6} carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M{sub 23}C{sub 6} carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.

  17. Microstructures and Surface Stabilities of {Ni-0.4C-6Ta- xCr, 0 ≤ x ≤ 50 Wt Pct} Cast Alloys at High Temperature

    Science.gov (United States)

    Berthod, Patrice

    2018-06-01

    Nickel-based cast alloys rich in chromium and reinforced by TaC carbides are potentially very interesting alloys for applications at elevated temperatures. Unfortunately, unlike cobalt-chromium and iron-chromium alloys, it is difficult to obtain exclusively TaC as primary carbides in Ni-Cr alloys. In alloys containing 30 wt pct Cr tantalum, carbides coexist with chromium carbides. The latter tend to weaken the alloy at elevated temperatures because they become rapidly spherical and then quickly lose their reinforcing effect. In this work, we attempted to stabilize TaC as a single carbide phase by testing different chromium contents in the [0, 50 wt pct] range. Six alloys containing 0.4C and 6Ta, weight contents corresponding to equivalent molar contents, were elaborated by foundry, and their as-cast microstructures were characterized. Samples of all alloys were exposed to 1127 °C and 1237 °C for 24 hours to characterize their stabilized microstructures. The surface fractions of chromium carbides and tantalum carbides were measured by image analysis, and their evolutions vs the chromium content were studied. For the chosen C and Ta contents, it appears that obtaining TaC only is possible by decreasing the chromium content to 10 wt pct. At the same time, TaC fractions are unfortunately too low because a large portion of tantalum integrates into the solid solution in the matrix. A second consequence is a critical decrease in oxidation resistance. Other possible methods to stabilize TaC as a single carbide are evocated, such as the simultaneous increase in Ta and decrease in chromium from 30 wt pct Cr.

  18. Effect of Cr3C2 content on the microstructure and properties of Mo2NiB2-based cermets

    International Nuclear Information System (INIS)

    Xie, Lang; Li, XiaoBo; Zhang, Dan; Yang, ChengMing; Yin, FuCheng; Xiangtan Univ., Hunan; Xiangtan Univ., Hunan; Xiao, YiFeng

    2015-01-01

    Four series of Mo 2 NiB 2 -based cermets with Cr 3 C 2 addition of between 0 and 7.5 wt.% in 2.5 wt.% increments were studied by means of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffractometry. The transverse rupture strength and hardness were also measured. It was found that Cr 3 C 2 completely dissolved in Mo 2 NiB 2 -based cermets. Cr 3 C 2 addition improved the wettability of the Ni binder phase on the Mo 2 NiB 2 hard phase, which resulted in a decrease in the porosity and an increase in the phase uniformity. The cermets with 2.5 wt.% Cr 3 C 2 content showed relatively fine grains and almost full density. A high Cr 3 C 2 content resulted in the formation of M 6 C (M = Mo, Cr, Ni) phase. In addition, energy dispersive X-ray spectroscopy results showed that the content of Mo in the binder decreased with increasing Cr 3 C 2 content. The cermets with 2.5 wt.% Cr 3 C 2 addition exhibited the highest transverse rupture strength of 2210 MPa, whereas the cermets without Cr 3 C 2 addition exhibited the highest hardness.

  19. Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

    International Nuclear Information System (INIS)

    Sarikaya, M.

    1979-06-01

    The effects of alloying elements and heat treatments on the microstructural changes and strength-toughness properties were investigated in optimization of vacuum melted Fe/Cr/C base steels. The structure of the steels in the as-quenched conditions consisted of highly dislocated autotempered lath martensite (strong phase) and thin continuous interlath films of retained austenite (tough phase). It has been emphasized again that the mechanical properties of the steels are sensitive to the amount and the stability of retained austenite. To increase the stability of retained austenite in the as-quenched condition 2 w/o Mn or 2 w/o Ni was added to the base steel, viz., Fe/3Cr/0.3C. Partial replacement of Cr by about 0.5 w/o Mo did not alter the beneficial microstructure

  20. New homo- and heteroleptic derivatives of trivalent ytterbium containing anion-radical 1,4-diazadiene ligands. Synthesis, properties and crystal structure of (C9H7)2Yb[2-MeC6H4NC(Me)C(Me)NC6H4Me-2] and [PhNC(Ph)C(Ph)NPh]3Yb complexes

    International Nuclear Information System (INIS)

    Gudilenkov, I.D.; Fukin, G.K.; Cherkasov, A.V.; Shavyrin, A.S.; Trifonov, A.A.; Larionova, Yu.E.

    2008-01-01

    Reaction of ytterbium bisindenyl complex (C 9 H 7 ) 2 Yb II (THF) 2 (1) with 1,4-diazabutadiene 2-MeC 6 H 4 N=C(Me)-C(Me)=NC 6 H 4 Me-2 ( Me DAD) is accompanied by the oxidation of metal atom until trivalent state and results in the formation of paramagnetic compound of metallocenes type (C 9 H 7 ) 2 Yb III ( Me DAD -. ) (3) containing 1,4-diazabutadiene anion-radical. Structure of complex 3 is ascertained by the X-ray structure analysis. Reactions of bisindenyl (1) and bisfluorenyl (C 13 H 9 ) 2 Yb II (THF) 2 (2) derivatives of bivalent ytterbium with 1,4-diazabutadiene PhN=C(Ph)-C(Ph)=NPh ( Ph DAD) (at 1:2 molar ratio of reagents) proceed with the complete break of Yb-C bonds, oxidation of ytterbium atom until trivalent state, and result in the formation of homoligand complex ( Ph DAD -. ) 3 Yb (6) containing three anion-radical 1,4-diazadiene ligands. Complex 6 was also prepared by the exchange reaction of YbCl 3 with Ph DAD -. K + (1:3) in THF. Complex 6 is characterized by the X-ray structure analysis [ru

  1. Syntheses of (6- sup 14 C) and (5-carboxy, 6- sup 14 C sub 2 )nitrendipine

    Energy Technology Data Exchange (ETDEWEB)

    Maul, N.; Scherling, D. (Bayer AG, Wuppertal (Germany, F.R.). Inst. fuer Pharmakologie)

    1989-04-01

    (6-{sup 14}C)Nitrendipine synthesis started from barium({sup 14})carbonate, which was converted to (1-{sup 14}C)acetyl chloride. The acid chloride was condensed with Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione). The resulting intermediate was treated with boiling methanol to give methyl (3-{sup 14}C)acetoacetate. The reaction with gaseous ammonia in toluene yielded the corresponding methyl 3-amino(3-{sup 14}C)crotonate which was condensed with ethyl 2-(3-nitro-benzylidene) acetoacetate to obtain (6-{sup 14}C)nitrendipine. (author).

  2. Learning Discloses Abnormal Structural and Functional Plasticity at Hippocampal Synapses in the APP23 Mouse Model of Alzheimer's Disease

    Science.gov (United States)

    Middei, Silvia; Roberto, Anna; Berretta, Nicola; Panico, Maria Beatrice; Lista, Simone; Bernardi, Giorgio; Mercuri, Nicola B.; Ammassari-Teule, Martine; Nistico, Robert

    2010-01-01

    B6-Tg/Thy1APP23Sdz (APP23) mutant mice exhibit neurohistological hallmarks of Alzheimer's disease but show intact basal hippocampal neurotransmission and synaptic plasticity. Here, we examine whether spatial learning differently modifies the structural and electrophysiological properties of hippocampal synapses in APP23 and wild-type mice. While…

  3. Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2013-01-10

    Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

  4. The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films

    International Nuclear Information System (INIS)

    Xiong, Y.; Song, J.; Luo, D.; Lei, Q.; Chen, C.

    2015-01-01

    The prevention of tritium losses via permeation through structure components is an important issue in fusion technology. The production of thin layers on materials with low diffusivity and/or low surface recombination constants (so-called permeation barriers) seems to be the most practical method to reduce or hinder the permeation of tritium through materials. TiN+TiC+TiN multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel by ion-beam assisted deposition technology. The characteristics of films are tested by XPS ASEM and XRD, which shows that the film are compact and uniform with a thickness of about 15 μm, and have a good adherence with the substrate below 773 K. The diffraction peaks in the XRD patterns for TiC and TiN are broadened, implying that the multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel. Meanwhile, the C-H bonded CH 4 -appears in the infrared spectra of multiple films, suggesting that the CH 4 - is in a static state, so hydrogen atom cannot migrate from the site bonded with carbon to a neighboring site. The measured deuterium permeability in 1Cr18Ni9Ti stainless steel coated with multiple films is 2-3 orders of magnitude lower than that of pure 1Cr18Ni9Ti stainless steel substrate from 473 K to 773 K. However, this barrier is partly destroyed above 773 K

  5. Surface stabilized GMR nanorods of silver coated CrO2 synthesized via a polymer complex at ambient pressure

    International Nuclear Information System (INIS)

    Biswas, S.; Singh, G.P.; Ram, S.; Fecht, H.-J.

    2013-01-01

    Stable anisotropic nanorods of surface modified CrO 2 (∼18 nm diameter) with a correlated diamagnetic layer (2–3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr 4+ ions by Ag atoms on the CrO 2 surface (topotactic surface layer) via an etching reaction of a CrO 2 -polymer complex with Ag + ions in hot water followed by heating the dried sample at 300–400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO 2 such that it no longer converts to Cr 2 O 3 in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO 2 structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d 5/2 and 3d 3/2 X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (−) 7.6% at 77 K, than reported values in compacted CrO 2 powders or composites. Such a large MR-value in the Coulomb blockade regime ( 2 nanorods. - Highlights: • Synthesis and structural studies of a novel GMR material of Ag coated CrO 2 . • Tailoring useful GMR property in CrO 2 nanorods of controlled shape and anisotropy. • Enhanced GMR is explained in correlation to the surface structure of CrO 2 nanorods

  6. Effect of various heat treatments on microstructure and mechanical properties of 34CrNiMo6 steel

    International Nuclear Information System (INIS)

    Abd El-Azim, M.E.; Ghoneim, M.M.; Nasreldin, A.M.; Soliman, S.

    1997-01-01

    Three different austenitization treatments were applied to high strength 34CrNiMo6 steel: conventional austenitization (CAT), high temperature austenitization (HTA) and duplex treatment (DT). It was found that DT structure has finer prior austenite grain size (30 μm) than those of HTA (200 μm) and CAT (70 μm) structures. DT and HTA structures have coarser lath size for martensite than CAT structure. DT results in higher room temperature impact toughness than HTA and CAT structures and shifts the ductile-brittle transition to lower temperatures by 14 K and 32 K in comparison with HTA and CAT structures, respectively. However, DT structure has intermediate values of room temperature yield stress and ultimate tensile strength between those of CAT and HTA structures. When this steel was tempered at 300 and 400 C it underwent tempered martensite embrittlement associated with intergranular fracture. (orig.)

  7. Structure and magnetic properties of Cr nanoparticles and Cr2O3 nanoparticles

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Zhang, Z.D.; Tegus, O.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Buschow, K.H.J.

    2005-01-01

    We have synthesized Cr nanoparticles by arc-discharge and Cr 2 O 3 nanoparticles by subsequent annealing the as-prepared Cr nanoparticles. The structure of these nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope. Most of the particles show a good crystal habit of well-defined cubic or orthorhombic shape, while some small particles show spherical shape. The as-prepared Cr nanoparticles have a BCC Cr core coated with a thin Cr 2 O 3 layer. Cr in the core of the particles heated at 873 K for 4 h is changed to Cr 2 O 3 . The results of magnetic measurements show that the Cr nanoparticles exhibit mainly antiferromagnetic properties, in addition to a weak-ferromagnetic component at lower fields. The weak-ferromagnetic component may be ascribed to uncompensated surface spins. For the field-cooled Cr 2 O 3 nanoparticles, an exchange bias is observed in the hysteresis loops, which can be interpreted as the exchange coupling between the uncompensated spins at the surface and the spins in the core of the Cr 2 O 3 nanoparticles

  8. One-pot tandem Ugi-4CR/S(N)Ar approach to highly functionalized quino[2,3-b][1,5]benzoxazepines.

    Science.gov (United States)

    Ghandi, Mehdi; Zarezadeh, Nahid; Abbasi, Alireza

    2016-05-01

    We have developed a convenient and facile method for the synthesis of functionalized diverse quino[2,3-b][1,5]benzoxazepines. These new compounds were synthesized through a one-pot sequential Ugi-4CR/base-free intramolecular aromatic nucleophilic substitution (S(N)Ar) reaction in moderate to good yields from readily available starting materials. Structural confirmation of the products is confirmed by analytical data and X-ray crystallography.

  9. Heat treatment for improvement in lower temperature mechanical properties of 0.40 pct C-Cr-Mo ultrahigh strength steel

    Science.gov (United States)

    Tomita, Yoshiyuki; Okabayashi, Kunio

    1983-11-01

    In the previous paper, it was reported that isothermal heat treatment of a commercial Japanese 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel (AISI 4340 type) at 593 K for a short time followed by water quenching, in which a mixed structure of 25 vol pct lower bainite and 75 vol pct martensite is produced, results in the improvement of low temperature mechanical properties (287 to 123 K). The purpose of this paper is to study whether above new heat treatment will still be effective in commercial practice for improving low temperature mechanical properties of the ultrahigh strength steel when applied to a commercial Japanese 0.40 pct C-Cr-Mo ultrahigh strength steel which is economical because it lacks the expensive nickel component (AISI 4140 type). At and above 203 K this new heat treatment, as compared with the conventional 1133 K direct water quenching treatment, significantly improved the strength, tensile ductility, and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel. At and above 203 K the new heat treatment also produced superior fracture ductility and notch toughness results at similar strength levels as compared to those obtained by using γ α' repetitive heat treatment for the same steel. However, the new heat treatment remarkably decreased fracture ductility and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel below 203 K, and thus no significant improvement in the mechanical properties was noticeable as compared with the properties produced by the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment. This contrasts with the fact that the new heat treatment, as compared with the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment, dramatically improved the notch toughness of the 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel, providing a better combination of strength and ductility throughout the 287 to 123 K temperature range. The difference

  10. Closure Report for Corrective Action Unit 330: Areas 6, 22, and 23 Tanks and Spill Sites, Nevada Test Site, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    A. T. Urbon

    2003-07-01

    This Closure Report (CR) documents the activities performed to close Corrective Action Unit (CAU) 330: Areas 6, 22, and 23 Tanks and Spill Sites, in accordance with the Federal Facility Agreement and Consent Order (FFACO of 1996), and the Nevada Division of Environmental Protection (NDEP)-approved Streamlined Approach for Environmental Restoration (SAFER) Plan for CAU 330: Areas 6, 22, and 23 Tanks and Spill Sites, Nevada Test Site (NTS), Nevada (U.S. Department of Energy, National Nuclear Security Administration Nevada Operation Office [NNSA/NV], 2001). CAU 330 consists of the following four Corrective Action Sites (CASs): 06-02-04, 22-99-06, 23-01-02, and 23-25-05 (Figure 1).

  11. Thermal, magnetic, and structural properties of soft magnetic FeCrNbCuSiB alloy ribbons

    International Nuclear Information System (INIS)

    Rosales-Rivera, A.; Valencia, V.H.; Quintero, D.L.; Pineda-Gomez, P.; Gomez, M.

    2006-01-01

    The thermal, magnetic and structural properties of amorphous magnetic Fe 73.5-x Cr x Nb 3 Cu 1 Si 13.5 B 9 alloy ribbons, with x=0, 2, 4, 6, 8, and 10, were studied by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magneto-impedance measurements and X-ray diffraction (XRD). The ribbons exhibit ultrasoft magnetic behavior, especially giant magneto-impedance effect, GMI. A three-peak behavior was observed in GMI curves. Particular attention has been given to observation of crystallization kinetics via DSC and TGA. The primary crystallization T pcr , and Curie T c , temperatures were determined from DSC and TGA data, respectively. The effect of partial substitution of iron by Cr on the thermal and magnetic properties is discussed

  12. Deletion of meso-2,3-butanediol dehydrogenase gene budC for enhanced D-2,3-butanediol production in Bacillus licheniformis

    Science.gov (United States)

    2014-01-01

    Background D-2,3-butanediol has many industrial applications such as chiral reagents, solvents, anti-freeze agents, and low freezing point fuels. Traditional D-2,3-butanediol producing microorganisms, such as Klebsiella pneumonia and K. xoytoca, are pathogenic and not capable of producing D-2,3-butanediol at high optical purity. Bacillus licheniformis is a potential 2,3-butanediol producer but the wild type strain (WX-02) produces a mix of D- and meso-type isomers. BudC in B. licheniformis is annotated as 2,3-butanediol dehydrogenase or acetoin reductase, but no pervious experiment was performed to verify this hypothesis. Results We developed a genetically modified strain of B. licheniformis (WX-02 ΔbudC) as a D-2,3-butanediol producer with high optimal purity. A marker-less gene deletion protocol based on a temperature sensitive knock-out plasmid T2-Ori was used to knock out the budC gene in B. licheniformis WX-02. The budC knock-out strain successfully abolished meso-2,3-butanediol production with enhanced D-2,3-butanediol production. No meso-BDH activity was detectable in cells of this strain. On the other hand, the complementary strain restored the characteristics of wild strain, and produced meso-2,3-butanediol and possessed meso-BDH activity. All of these data suggested that budC encoded the major meso-BDH catalyzing the reversible reaction from acetoin to meso-2,3-butanediol in B. licheniformis. The budC knock-out strain produced D-2,3-butanediol isomer only with a high yield of 30.76 g/L and a productivity of 1.28 g/L-h. Conclusions We confirmed the hypothesis that budC gene is responsible to reversibly transfer acetoin to meso-2,3-butanediol in B. licheniformis. A mutant strain of B. licheniformis with depleted budC gene was successfully developed and produced high level of the D-2,3-butanediol with high optimal purity. PMID:24475980

  13. Microstructure and properties of FeSiCr/PA6 composites by injection molding using FeSiCr powders by phosphating and coupling treatment

    Science.gov (United States)

    Wang, Lulu; Qiao, Liang; Zheng, Jingwu; Cai, Wei; Ying, Yao; Li, Wangchang; Che, Shenglei; Yu, Jing

    2018-04-01

    FeSiCr/PA6 composites were prepared by injection molding using the FeSiCr powders modified by different phosphating agents and KH550 coupling agent. The resistivity, impact strength, magnetic permeability and magnetic loss of the FeSiCr/PA6 composites were measured. The morphologies of different FeSiCr powders and the FeSiCr/PA6 composites were also observed by scanning electron microscope (SEM). The results showed that 1-Hydroxyethylidene-1,1-diphosphonic acid, phytic acid and H3PO4 could improve the electrical resistivity of FeSiCr powders by forming the dense phosphating layer except diphenylphosphinic acid. However, the resistivity of FeSiCr/PA6 composites using the FeSiCr powders treated by all the four phosphating agents had no obvious increase though the phosphating layer on the surface of FeSiCr powder came into being. The nylon insulation layer had much stronger influence than the phosphating layer on electrical resistivity of the composites. After adding appropriate KH550 coupling agent, the impact strengths of FeSiCr/PA6 composites were significantly improved, which may be associated with the tiny gap between FeSiCr powder and PA6 matrix. The effects of the phosphating agents on the magnetic permeability and loss of the FeSiCr/PA6 were small and the mechanism were also discussed.

  14. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001).

    Science.gov (United States)

    Li, Lianbi; Zang, Yuan; Hu, Jichao; Lin, Shenghuang; Chen, Zhiming

    2017-05-25

    The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL) on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001) Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm², the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm². Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  15. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001

    Directory of Open Access Journals (Sweden)

    Lianbi Li

    2017-05-01

    Full Text Available The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001 Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 <21-1> at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm2, the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm2. Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  16. New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

    International Nuclear Information System (INIS)

    Weng Shengfeng; Wang, Yun-Hsin; Lee, Chi-Shen

    2012-01-01

    Two novel materials, [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1-bar (No. 2); compound 2 crystallized in monoclinic space group P2 1 /c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of Cu II ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d 1 excited state and two levels of the 4f 1 ground state ( 2 F 5/2 and 2 F 7/2 ). Compounds 1b and 2 containing Ce III ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers. - Graphical Abstract: [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2)—with 1D and 2D structures were synthesized and characterized. Highlights: ► Two MOF – [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2) – with 1D and 2D structures. ► The adjacent chains of the 1D framework were correlated with each other through an oxalate ligand to form a 2D layer structure. ► The source of the oxalate ligand was the decomposition in situ of citric acid oxidized in the presence of Cu II ions.

  17. The Role of Carbon in Grain Refinement of Cast CrFeCoNi High-Entropy Alloys

    Science.gov (United States)

    Liu, X. W.; Liu, L.; Liu, G.; Wu, X. X.; Lu, D. H.; Yao, J. Q.; Jiang, W. M.; Fan, Z. T.; Zhang, W. B.

    2018-06-01

    As a promising engineering material, high-entropy alloys (HEAs) CrFeCoNi system has attracted extensive attention worldwide. Their cast alloys are of great importance because of their great formability of complex components, which can be further improved through the transition of the columnar to equiaxed grains and grain refinement. In the current work, the influence of C contents on the grain structures and mechanical properties of the as-cast high-entropy alloy CrFeCoNi was chosen as the target and systematically studied via a hybrid approach of the experiments and thermodynamic calculations. The alloys with various C additions were prepared by arc melting and drop cast. The as-cast macrostructure and microstructure were characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The cast HEAs transform from coarse columnar grains into equiaxed grains with the C level increased to ≥ 2 at. pct and the size of equiaxed grains is further decreased with the increasing C addition. It is revealed that the interdendritic segregation of Cr and C results in grain boundary precipitation of M23C6 carbides. The grain refinement is attributed to the additional constitutional supercoiling from the C addition. The yield stress and tensile strength at room temperature are improved due to the transition of columnar to equiaxed grains and grain refinement.

  18. Structural, magnetic and transport properties of Pb{sub 2}Cr{sub 1+x}Mo{sub 1−x}O{sub 6} (−1≤x≤1/3)

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, H.F. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Mathematics and Physics, University of Science and Technology, Beijing 100083 (China); Cao, L.P. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Song, Y.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Mathematics and Physics, University of Science and Technology, Beijing 100083 (China); Feng, S.M.; Shen, X. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Ni, X.D. [School of Mathematics and Physics, University of Science and Technology, Beijing 100083 (China); Yao, Y.; Wang, Y.G. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, R.M. [School of Mathematics and Physics, University of Science and Technology, Beijing 100083 (China); Jin, C.Q. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yu, R.C., E-mail: rcyu@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2017-02-15

    Pb{sub 2}Cr{sub 1+x}Mo{sub 1-x}O{sub 6} (−1≤x≤1/3) samples were synthesized via a high pressure and high temperature route. X-ray diffraction results suggest the samples crystallize in a disordered double perovskite structure (Pm-3m). X-ray photoemission spectroscopy results confirm the presence of Mo{sup 4+} for x=−1 and Mo{sup 6+} for x=1/3. The measured magnetic and electrical properties exhibit systematic change with increasing x. - Highlights: • A series of Pb{sub 2}Cr{sub 1+x}Mo{sub 1−x}O{sub 6} samples were synthesized under high pressure. • Magnetic and electrical properties of the series samples were investigated. • Valence states of Cr and Mo were determined through the analyses of XRD and XPS results. • Ground state of PbMoO{sub 3} were determined through the transport study and first-principles calculations.

  19. Structural and magnetic properties of Co films on highly textured and randomly oriented C_6_0 layers

    International Nuclear Information System (INIS)

    Kim, Dong-Ok; Choi, Jun Woo; Lee, Dong Ryeol

    2016-01-01

    The structural and magnetic properties of Co/C_6_0/pentacene and Co/C_6_0 thin film structures were investigated. Atomic force microscopy and x-ray reflectivity analysis show that the presence or absence of a pentacene buffer layer leads to a highly textured or randomly oriented C_6_0 layer, respectively. A Co film deposited on a randomly oriented C_6_0 layer penetrates into the C_6_0 layer when it is deposited at a slow deposition rate. The Co penetration can be minimized, regardless of the Co deposition rate, by growth on a highly textured and nanostructured C_6_0/pentacene layer. Vibrating sample magnetometry measurements show that the saturation magnetization of Co/C_6_0/pentacene is significantly reduced compared to that of Co/C_6_0. On the other hand, the Co penetration does not seem to have an effect on the magnetic properties, suggesting that the structural properties of the Co and C_6_0 layer, rather than the Co penetration into the organic C_6_0 layer, are critical to the magnetic properties of the Co/C_6_0. - Highlights: • Structural and magnetic properties of metal(Co)-organic(C_6_0) interface is studied. • Highly textured C_6_0 layer was grown on a pentacene buffer layer (C_6_0/pentacene). • Co penetration into the C_6_0 is significantly suppressed in Co/C_6_0/pentacene. • The Co magnetization in Co/C_6_0/pentacene is reduced than that in Co/C_6_0.

  20. Efficient band structure modulations in two-dimensional MnPSe3/CrSiTe3 van der Waals heterostructures

    Science.gov (United States)

    Pei, Qi; Wang, Xiaocha; Zou, Jijun; Mi, Wenbo

    2018-05-01

    As a research upsurge, van der Waals (vdW) heterostructures give rise to numerous combined merits and novel applications in nanoelectronics fields. Here, we systematically investigate the electronic structure of MnPSe3/CrSiTe3 vdW heterostructures with various stacking patterns. Then, particular attention of this work is paid on the band structure modulations in MnPSe3/CrSiTe3 vdW heterostructures via biaxial strain or electric field. Under a tensile strain, the relative band edge positions of heterostructures transform from type-I (nested) to type-II (staggered). The relocation of conduction band minimum also brings about a transition from indirect to direct band gap. Under a compressive strain, the electronic properties change from semiconducting to metallic. The physical mechanism of strain-dependent band structure may be ascribed to the shifts of the energy bands impelled by different superposition of atomic orbitals. Meanwhile, our calculations manifest that band gap values of MnPSe3/CrSiTe3 heterostructures are insensitive to the electric field. Even so, by applying a suitable intensity of negative electric field, the band alignment transition from type-I to type-II can also be realized. The efficient band structure modulations via external factors endow MnPSe3/CrSiTe3 heterostructures with great potential in novel applications, such as strain sensors, photocatalysis, spintronic and photoelectronic devices.

  1. Hot corrosion of Co-Cr, Co-Cr-Al, and Ni-Cr alloys in the temperature range of 700-750 deg C

    Science.gov (United States)

    Chiang, K. T.; Meier, G. H.

    1980-01-01

    The effect of SO3 pressure in the gas phase on the Na2SO4 induced hot corrosion of Co-Cr, Ni-Cr, and Co-Cr-Al alloys was studied in the temperature range 700 to 750 C. The degradation of the Co-Cr and Ni-Cr alloys was found to be associated with the formation of liquid mixed sulfates (CoSO4-Na2SO4 or NiSO4-Na2SO4) which provided a selective dissolution of the Co or Ni and a subsequent sulfidation oxidation mode of attack which prevented the maintenance of a protective Cr2O3 film. A clear mechanism was not developed for the degradation of Co-Cr-Al alloys. A pitting corrosion morphology was induced by a number of different mechanisms.

  2. Experimental and numerical analysis of the static and dynamic crack growth resistance behaviour of structural steels in the temperature range from 20 C to 350 C; Experimentelle und numerische Untersuchungen des statischen und dynamischen Risswiderstandsverhaltens verschiedener hoeherfester Baustaehle im Temperaturbereich von 20 C bis 350 C

    Energy Technology Data Exchange (ETDEWEB)

    Aurich, D.; Gerwien, P.; Huenecke, J.; Klingbeil, D.; Krafka, H.; Kuenecke, G.; Ohm, K.; Veith, H.; Wossidlo, P. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Haecker, R.; 1

    1998-11-01

    The crack growth resistance behaviour of the steels StE 460 and 22NiMoCr3-7 was determined in the temperature range from 23 C to 350 C by means of C(T), M(T), and ISO-V specimens tested under quasistatic and dynamic loads. The Russian steel 15Ch2NMFA-A was tested at room temperature and 50 C. In the steels StE 460 and 22 NiMoCr3-7, the minimum crack growth resistance is observed at about 250 C, with measured values always being higher for the latter steel type. The crack growth resistance behaviour of the tested materials correlates with the behaviour of flow curve, yield strength, and notch impact toughness as a function of temperature. Impact tests of ISO-V specimens give higher crack resistance values than quasistatic load tests, and the temperature dependence is significantly lower than those of specimens tested under static loads. A metallurgical analysis of the materials shows the causes of the dissimilar behaviour. The stretching zones determined for the C(T) specimen correspond to the toughness of the steels examined, and they are not much influenced by the temperature. The numerical analysis using damaging models for simulation of ductile crack growth is reported for all specimen types and two different temperatures each. (orig./CB) [Deutsch] Mit C(T)-, M(T)- sowie quasistatisch und dynamisch geprueften ISO-V-Proben wurde das Risswiderstandsverhalten fuer die Staehle StE 460 und 22NiMoCr3-7 im Temperaturbereich von 23 C bis 350 C ermittelt, waehrend der russische Stahl 15Ch2NMFA-A fuer Raumtemperatur und fuer 50 C untersucht wurde. Das Minimum der Risszaehigkeit stellt sich bei StE 460 und 22 NiMoCr3-7 um etwa 250 C ein, wobei die Werte fuer den 22NiMoCr3-7 bei allen Temperaturen wesentlich hoeher liegen als beim StE 460. Dabei korreliert das Risswiderstandsverhalten der untersuchten Werkstoffe mit dem Verhalten von Fliesskurven, Streckgrenzen und Kerbschlagzaehigkeiten in Abhaengigkeit von der Temperatur. Schlagartig beanspruchte ISO-V-Proben liefern

  3. High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

    Science.gov (United States)

    Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

    2015-03-01

    Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

  4. Robust Strategy for Crafting Li5Cr7Ti6O25@CeO2 Composites as High-Performance Anode Material for Lithium-Ion Battery.

    Science.gov (United States)

    Mei, Jie; Yi, Ting-Feng; Li, Xin-Yuan; Zhu, Yan-Rong; Xie, Ying; Zhang, Chao-Feng

    2017-07-19

    A facile strategy was developed to prepare Li 5 Cr 7 Ti 6 O 25 @CeO 2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO 2 coating does not alter the structure of Li 5 Cr 7 Ti 6 O 25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO 2 layer successfully formed a coating layer on a surface of Li 5 Cr 7 Ti 6 O 25 particles and supplied a good conductive connection between the Li 5 Cr 7 Ti 6 O 25 particles. The electrochemical characterization reveals that Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li 5 Cr 7 Ti 6 O 25 only delivers an initial delithiation capacity of ∼94.7 mAh g -1 , and the delithiation capacity merely achieves 87.4 mAh g -1 even after 100 cycles. However, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g -1 , and the delithiation capacity also reaches 100.5 mAh g -1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li 5 Cr 7 Ti 6 O 25 at large current densities.

  5. A tri-junction diffusion couple analysis of the Nb-Cr-Ti system at 950{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Thoma, D.J. [Los Alamos National Lab., NM (United States); Perepezko, J.H. [Wisconsin Univ., Madison, WI (United States). Dept. of Materials Science and Engineering

    1993-11-01

    With a three-way diffusion couple consisting of a tri-junction between three elements, a whole spectrum of phase development and ternary equilibria is available within a single isothermal sample. Binary equilibria (for the three binary systems) are also available in single sample by analyzing diffusion zones at composition limits outside the field of ternary interaction. The tri-junction approach was employed to evaluate ternary phase formation, ternary solubility limits of binary phases, and diffusion paths in a candidate high-temperature structural system (Nb-Cr-Ti). Ternary phase equilibria and tie lines have been defined at 950C and results confirmed with isothermal anneals of two-phase ternary alloys. The continuous solubility in TiCr{sub 2}-NbCr{sub 2} region is broadened by at least 5 at. % from binary intermetallic phase fields. No new ternary phases were detected in the Nb-CrTi system at 950C. By examining the relative shifts in the diffusion interfaces, a qualitative ranking of interdiffusion suggests that addition of Nb restricts diffusion of Cr into Ti compared to binary (Cr/Ti) behavior.

  6. Observation of magnetization and exchange bias reversals in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sharannia, M.P.; De, Santanu [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Singh, Ripandeep; Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Nirmala, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Santhosh, P.N., E-mail: santhosh@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2017-05-15

    Polycrystalline NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} has orthorhombic structure with Pnma space group and is magnetically ordered at room temperature as confirmed by neutron diffraction. The magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} shows magnetization reversal and sign reversal of exchange bias at ~16 K. Nd{sup 3+} moments that get induced by the internal field of |Fe+Cr| sublattice couple antiferromagnetically with the ferromagnetic component of |Fe+Cr| sublattice. Nd{sup 3+} moments overcome the |Fe+Cr| moments at ~16 K below which the material shows negative magnetization and positive exchange bias. - Highlights: • Neutron diffraction confirms magnetic ordering at 300 K in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}. • Magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. • Nd{sup 3+} moments couple antiferromagnetically with |Fe+Cr| ferromagnetic moments. • Shows magnetization reversal and exchange bias reversal.

  7. Structure determination from small crystals of two aluminophosphates, CrAPO-14 and SAPO-43

    International Nuclear Information System (INIS)

    Helliwell, M.; Kaucic, V.; Cheetham, G.M.T.; Harding, M.M.; Kariuki, B.M.; Rizkallah, P.J.

    1993-01-01

    Small single crystals, ca 10 5 μm 3 , of two aluminophosphates have been used to determine their structures. Both compounds were synthesized with the aim of incorporating chromium into the framework, and for CrAPO-14 the X-ray diffraction results show that this has been achieved. For CrAPO-14, Al 3.96 Cr 0.04 (PO 4 ) 4 (OH).C 3 H 10 N.H 2 O, data recorded on a Rigaku AFC-5R diffractometer (Cu Kα) and, independently, on an Enraf-Nonius FAST diffractometer (Mo Kα), showed the structure to be like that of GaPO-14; aluminium atoms occupy four-, five- and six-coordinated sites, and 4-5% of the aluminium in the six-coordinate site is replaced by chromium. For SAPO-43, Al 2 (PO 4 ) 2 (C 3 H 10 N), data were recorded independently on the AFC-5R (Cu Kα) and on a FAST diffractometer with synchrotron radiation of wavelength 0.895 A; the structure is like that of gismondin, but replacement of Al by Cr to a significant extent could not be established. Framework Al, P and O atoms are located with e.s.d.'s of 0.001-0.005 A, template atoms with e.s.d.'s of ca 0.01 A in CrAPO-14, and larger e.s.d.'s in SAPO-43 where there is disorder in the template-molecule position. In all these respects the two independent determinations for each structure are in agreement. The effectiveness of the different methods of intensity-data collection is compared. (orig.)

  8. The local structure, magnetic, and transport properties of Cr-doped In2O3 films

    International Nuclear Information System (INIS)

    Wang Shiqi; An Yukai; Feng Deqiang; Liu Jiwen; Wu Zhonghua

    2013-01-01

    Cr-doped In 2 O 3 films were deposited on Si (100) substrates by RF-magnetron sputtering technique. The local structure, magnetic, and transport properties of films are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption fine structure, Hall effect, R-T, and magnetic measurements. Structural analysis clearly indicates that Cr ions substitute for In 3+ sites of the In 2 O 3 lattice in the valence of +2 states and Cr-related secondary phases or clusters as the source of ferromagnetism is safely ruled out. The films with low Cr concentration show a crossover from semiconducting to metallic transport behavior, whereas only semiconducting behavior is observed in high Cr concentration films. The transport property of all films is governed by Mott variable range hopping behavior, suggesting that the carriers are strongly localized. Magnetic characterizations show that the saturated magnetization of films increases first, and then decreases with Cr doping, while carrier concentration n c decreases monotonically, implying that the ferromagnetism is not directly induced by the mediated carriers. It can be concluded the ferromagnetism of films is intrinsic and originates from electrons bound in defect states associated with oxygen vacancies.

  9. Cr{sub 2}O{sub 5} as new cathode for rechargeable sodium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xu-Yong; Chien, Po-Hsiu; Rose, Alyssa M.; Zheng, Jin [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Hung, Ivan; Gan, Zhehong [Centre of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310 (United States); Hu, Yan-Yan, E-mail: hu@chem.fsu.edu [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Centre of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310 (United States)

    2016-10-15

    Chromium oxide, Cr{sub 2}O{sub 5}, was synthesized by pyrolyzing CrO{sub 3} at 350 °C and employed as a new cathode in rechargeable sodium ion batteries. Cr{sub 2}O{sub 5}/Na rechargeable batteries delivered high specific capacities up to 310 mAh/g at a current density of C/16 (or 20 mA/g). High-resolution solid-state {sup 23}Na NMR both qualitatively and quantitatively revealed the reversible intercalation of Na ions into the bulk electrode and participation of Na ions in the formation of the solid-electrolyte interphase largely at low potentials. Amorphization of the electrode structure occurred during the first discharge revealed by both NMR and X-ray diffraction data. CrO{sub 3}-catalyzed electrolyte degradation and loss in electronic conductivity led to gradual capacity fading. The specific capacity stabilized at >120 mAh/g after 50 charge-discharge cycles. Further improvement in electrochemical performance is possible via electrode surface modification, polymer binder incorporation, or designs of new morphologies. - Graphical abstract: Electrochemical profile of a Cr{sub 2}O{sub 5}/Na battery cell and high-resolution solid-state {sup 23}Na MAS NMR spectrum of a Cr{sub 2}O{sub 5} electrode discharged to 2 V. - Highlights: • Cr{sub 2}O{sub 5} was synthesized and used as a new cathode in rechargeable Na ion batteries. • A high capacity of 310 mAh/g and an energy density of 564 Wh/kg were achieved. • High-resolution solid-state {sup 23}Na NMR was employed to follow the reaction mechanisms.

  10. Influence of boron vacancies on phase stability, bonding and structure of MB2 (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2 type structure

    International Nuclear Information System (INIS)

    Dahlqvist, Martin; Rosen, Johanna; Jansson, Ulf

    2015-01-01

    Transition metal diborides in hexagonal AlB 2 type structure typically form stable MB 2 phases for group IV elements (M  =  Ti, Zr, Hf). For group V (M  =  V, Nb, Ta) and group VI (M  =  Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on the B-site in hexagonal MB 2 and its influence on the phase stability and the structure for TiB 2 , ZrB 2 , HfB 2 , VB 2 , NbB 2 , TaB 2 , CrB 2 , MoB 2 , and WB 2 using first-principles calculations. Selected phases are also analyzed with respect to electronic and bonding properties. We identify trends showing that MB 2 with M from group V and IV are stabilized when introducing B-vacancies, consistent with a decrease in the number of states at the Fermi level and by strengthening of the B–M interaction. The stabilization upon vacancy formation also increases when going from M in period 4 to period 6. For TiB 2 , ZrB 2 , and HfB 2 , introduction of B-vacancies have a destabilizing effect due to occupation of B–B antibonding orbitals close to the Fermi level and an increase in states at the Fermi level. (paper)

  11. Effects of V and Cr on Laser Cladded Fe-Based Coatings

    Directory of Open Access Journals (Sweden)

    Haiyang Wang

    2018-03-01

    Full Text Available Fe-based coatings with high V and Cr content were obtained by laser cladding using Fe-based powder with different Cr3C2 and FeV50 content. The results showed that Fe-based coatings were uniform and dense. The constituent phases were mainly composed of α-Fe solid solution with the increase of Cr3C2 and FeV50, γ-Fe and V8C7 phases were achieved. The microstructure of the coatings exhibited a typical dendrite structure. The concentration of C, V and Cr were saturated in dendritic areas, and the other alloying elements were mainly dissolved in the interdendritic areas. The hardness and wear resistance of Fe-based coatings were enhanced with the Cr3C2 and FeV50 addition. The specimen with 15% Cr3C2 and 16% FeV50 had the highest hardness of 66.1 ± 0.6 HRC, which was 1.05 times higher than the sample with 4.5% Cr3C2 and 5% FeV50, and the wear resistance of the former was three times greater than the latter.

  12. Pressure-induced spin reorientation transition in layered ferromagnetic insulator Cr2Ge2Te6

    Science.gov (United States)

    Lin, Zhisheng; Lohmann, Mark; Ali, Zulfikhar A.; Tang, Chi; Li, Junxue; Xing, Wenyu; Zhong, Jiangnan; Jia, Shuang; Han, Wei; Coh, Sinisa; Beyermann, Ward; Shi, Jing

    2018-05-01

    The anisotropic magnetoresistance (AMR) of Cr2Ge2Te6 (CGT), a layered ferromagnetic insulator, is investigated under an applied hydrostatic pressure up to 2 GPa. The easy-axis direction of the magnetization is inferred from the AMR saturation feature in the presence and absence of an applied pressure. At zero applied pressure, the easy axis is along the c direction or perpendicular to the layer. Upon application of a hydrostatic pressure > 1 GPa, the uniaxial anisotropy switches to easy-plane anisotropy which drives the equilibrium magnetization from the c axis to the a b plane at zero magnetic field, which amounts to a giant magnetic anisotropy energy change (> 100%). As the temperature is increased across the Curie temperature, the characteristic AMR effect gradually decreases and disappears. Our first-principles calculations confirm the giant magnetic anisotropy energy change with moderate pressure and assign its origin to the increased off-site spin-orbit interaction of Te atoms due to a shorter Cr-Te distance. Such a pressure-induced spin reorientation transition is very rare in three-dimensional ferromagnets, but it may be common to other layered ferromagnets with similar crystal structures to CGT, and therefore offers a unique way to control magnetic anisotropy.

  13. Crystal Structure of the Receptor-Binding Domain of Botulinum Neurotoxin Type HA, Also Known as Type FA or H.

    Science.gov (United States)

    Yao, Guorui; Lam, Kwok-Ho; Perry, Kay; Weisemann, Jasmin; Rummel, Andreas; Jin, Rongsheng

    2017-03-08

    Botulinum neurotoxins (BoNTs), which have been exploited as cosmetics and muscle-disorder treatment medicines for decades, are well known for their extreme neurotoxicity to humans. They pose a potential bioterrorism threat because they cause botulism, a flaccid muscular paralysis-associated disease that requires immediate antitoxin treatment and intensive care over a long period of time. In addition to the existing seven established BoNT serotypes (BoNT/A-G), a new mosaic toxin type termed BoNT/HA (aka type FA or H) was reported recently. Sequence analyses indicate that the receptor-binding domain (H C ) of BoNT/HA is ~84% identical to that of BoNT/A1. However, BoNT/HA responds differently to some potent BoNT/A-neutralizing antibodies (e.g., CR2) that target the H C . Therefore, it raises a serious concern as to whether BoNT/HA poses a new threat to our biosecurity. In this study, we report the first high-resolution crystal structure of BoNT/HA-H C at 1.8 Å. Sequence and structure analyses reveal that BoNT/HA and BoNT/A1 are different regarding their binding to cell-surface receptors including both polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Furthermore, the new structure also provides explanations for the ~540-fold decreased affinity of antibody CR2 towards BoNT/HA compared to BoNT/A1. Taken together, these new findings advance our understanding of the structure and function of this newly identified toxin at the molecular level, and pave the way for the future development of more effective countermeasures.

  14. Photocatalysis of Hg2+ y Cr6+ in waste waters

    International Nuclear Information System (INIS)

    Franco, Alexander; Ortiz, Natalia; Mejia, Gloria; Restrepo, Gloria; Penuela, Gustavo

    2001-01-01

    This work was carried out to propose a treatment for the elimination of Hg 2 + and Cr 6 + ions that are present in wastewaters of the CIA and ISA laboratories. These ions are present in waste waters because in these laboratories analysis of chemical oxygen demand (COD), are performed in which HgSO 4 and K 2 Cr 2 O 7 are used. COD is a parameter very important to evaluate. In this paper water pollution results of chemical reduction of Hg 2 + and Cr 6 + ions using photo catalysis are reported and the elimination of both ions by using an adsorbent

  15. The origin of anisotropy and high density of states in the electronic structure of Cr2GeC by means of polarized soft x-ray spectroscopy and ab initio calculations

    Science.gov (United States)

    Magnuson, Martin; Mattesini, Maurizio; Bugnet, Matthieu; Eklund, Per

    2015-10-01

    The anisotropy in the electronic structure of the inherently nanolaminated ternary phase Cr2GeC is investigated by bulk-sensitive and element selective soft x-ray absorption/emission spectroscopy. The angle-resolved absorption/emission measurements reveal differences between the in-plane and out-of-plane bonding at the (0001) interfaces of Cr2GeC. The Cr L 2, 3, C K, and Ge M 1, M 2, 3 emission spectra are interpreted with first-principles density-functional theory (DFT) including core-to-valence dipole transition matrix elements. For the Ge 4s states, the x-ray emission measurements reveal two orders of magnitude higher intensity at the Fermi level than DFT within the General Gradient Approximation (GGA) predicts. We provide direct evidence of anisotropy in the electronic structure and the orbital occupation that should affect the thermal expansion coefficient and transport properties. As shown in this work, hybridization and redistribution of intensity from the shallow 3d core levels to the 4s valence band explain the large Ge density of states at the Fermi level.

  16. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    International Nuclear Information System (INIS)

    Bollini, Carlos Guido; Giambiagi, Mario; Giambiagi, Myriam Segre de; Figueiredo, Aloysio Paiva de

    2001-02-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I ring values. (author)

  17. The E23K variant of Kir6.2 associates with impaired post-OGTT serum insulin response and increased risk of type 2 diabetes

    DEFF Research Database (Denmark)

    Nielsen, Eva-Maria D; Hansen, Lars; Carstensen, Bendix

    2003-01-01

    .013). In the present study, the association of the E23K polymorphism with type 2 diabetes was not significant (P = 0.26). However, the K23K genotype significantly associated with type 2 diabetes in a meta-analysis of white case and control subjects (n = 2,824, odds ratio [OR] 1.49, P = 0.00022). In conclusion......The E23K polymorphism of the pancreatic beta-cell ATP-sensitive K(+) (K(ATP)) channel subunit Kir6.2 (KCNJ11) is associated with type 2 diabetes in whites, and a recent in vitro study of the E23K variant suggests that the association to diabetes might be explained by a slight inhibition of serum...... 803 type 2 diabetic patients and 862 glucose-tolerant control subjects. The E23K variant was associated with significant reductions in the insulinogenic index (P = 0.022) and serum insulin levels under the response curve during an OGTT (0-120 min) (P = 0.014) as well as with an increase in BMI (P = 0...

  18. Mesoporous C/CrN and C/VN Nanocomposites Obtained by One-Pot Soft-Templating Process

    Directory of Open Access Journals (Sweden)

    Julien Kiener

    2016-07-01

    Full Text Available Nanocomposites of ordered mesoporous carbon associated with chromium nitride (CrN or vanadium nitride (VN nanoparticles were obtained by a simple one-pot synthesis based on the solvent evaporation induced self-assembly (EISA process using Pluronic triblock surfactant as soft-template and a phenol-based resin (resol as carbon precursor. These nanocomposites were characterized by X-ray diffraction, nitrogen physisorption and Transmission Electron Microscopy (TEM techniques. Electron tomography (or 3D-TEM technique was particularly useful for providing direct insight on the internal architecture of C/CrN nanocomposite. Nanocomposites showed a very well organized hexagonal mesoporous carbon structure and a relatively high concentration of nanoparticles well distributed in the porous network. The chromium and vanadium nitrides/mesoporous carbon nanocomposites could have many potential applications in catalysis, Li-ion batteries, and supercapacitors.

  19. Corrosion performance of Cr3C2-NiCr+0.2%Zr coated super alloys under actual medical waste incinerator environment

    Science.gov (United States)

    Ahuja, Lalit; Mudgal, Deepa; Singh, Surendra; Prakash, Satya

    2018-03-01

    Incineration techniques are widely used to dispose of various types of waste which lead to formation of very corrosive environment. Such corrosive environment leads to the degradation of the alloys used in these areas. To obviate this problem, zirconium modified Cr3C2-(NiCr) coating powder has been deposited on three superalloys namely Superni 718, Superni 600 and Superco 605 using Detonation gun technique. Corrosion test was conducted in actual medical waste incinerator environment. The samples were hung inside the secondary chamber operated at 1050°C for 1000h under cyclic condition. Corrosion kinetics was monitored using the weight gain measurements and thickness loss. Corrosion products were characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction technique. It was observed that coating is found to be successful in impeding the corrosion problem in superalloys.

  20. Electron microscopy characterization of Ni-Cr-B-Si-C laser deposited coatings.

    Science.gov (United States)

    Hemmati, I; Rao, J C; Ocelík, V; De Hosson, J Th M

    2013-02-01

    During laser deposition of Ni-Cr-B-Si-C alloys with high amounts of Cr and B, various microstructures and phases can be generated from the same chemical composition that results in heterogeneous properties in the clad layer. In this study, the microstructure and phase constitution of a high-alloy Ni-Cr-B-Si-C coating deposited by laser cladding were analyzed by a combination of several microscopy characterization techniques including scanning electron microscopy in secondary and backscatter imaging modes, energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The combination of EDS and EBSD allowed unequivocal identification of micron-sized precipitates as polycrystalline orthorhombic CrB, single crystal tetragonal Cr5B3, and single crystal hexagonal Cr7C3. In addition, TEM characterization showed various equilibrium and metastable Ni-B, Ni-Si, and Ni-Si-B eutectic products in the alloy matrix. The findings of this study can be used to explain the phase formation reactions and to tune the microstructure of Ni-Cr-B-Si-C coatings to obtain the desired properties.

  1. Formation, cationic site exchange and surface structure of mechanosynthesized EuCrO{sub 3} nanocrystalline particles

    Energy Technology Data Exchange (ETDEWEB)

    Widatallah, H M; Al-Harthi, S H; Gismelseed, A M; Al-Rawas, A D [Department of Physics, Sultan Qaboos University, PO Box 36, 123, Muscat (Oman); Johnson, C; Moore, E A [School of Chemistry and Analytical Sciences, The Open University, Milton Keynes, MK7 6AA (United Kingdom); Klencsar, Z [Chemical Research Center, Hungarian Academy of Sciences, 1025 Budapest (Hungary); Wynter, C I [Nassau Community College, Garden City, NY 11530-6793 (United States); Brown, D E, E-mail: hishammw@squ.edu.om, E-mail: hisham@ictp.it [Department of Physics, Northern Illinois University, De Kalb, IL 60115 (United States)

    2011-07-06

    Nanocrystalline EuCrO{sub 3} particles ({approx}25 nm) have been prepared by pre-milling a 1 : 1 molar mixture of Eu{sub 2}O{sub 3} and Cr{sub 2}O{sub 3} for 60 h followed by sintering at 700 {sup 0}C (12 h). This temperature is {approx}500-600 {sup 0}C lower than those at which the material, in bulk form, is conventionally prepared. Rietveld analysis of the x-ray powder diffraction pattern of the EuCrO{sub 3} nanoparticles favours a structural model involving a slight degree of cationic exchange where {approx}11% of the Eu{sup 3+} and Cr{sup 3+} ions exchange their normal dodecahedral A- and octahedral B-sites, respectively, in the perovskite-related structure. This cationic site exchange, which is unusual in a perovskite structure, has been well supported by the corresponding room-temperature {sup 151}Eu Moessbauer spectrum of the nanoparticles that in addition to displaying a distribution in the principal component of the EFG tensor (V{sub zz}) at the usual A-sites of the {sup 151}Eu nuclei, also revealed the presence of a subcomponent with {approx}11% area fraction and a considerably increased |V{sub zz}| value that was associated with Eu{sup 3+} ions at octahedral B-sites. X-ray photoelectron and Auger electron spectroscopic techniques reveal a complex surface structure where extremely thin layers of un-reacted Eu{sub 2}O{sub 3} and Cr{sub 2}O{sub 3} cover most of the EuCrO{sub 3} nanoparticles' surfaces together with some traces of elemental Cr. The binding energies associated with Eu{sup 3+} 3d{sub 5/2}, Eu{sup 3+} 4d{sub 3/2}, Cr{sup 3+} 2p{sub 3/2} and O{sup 2-} 1s core-level electrons in EuCrO{sub 3} are estimated from the x-ray photoelectron data for the first time.

  2. Lithium Insertion in LiCr3O8, NaCr3O8, and KCr3O8 at Room Temperature and at 125°C

    DEFF Research Database (Denmark)

    Koksbang, R.; Fauteux, D.; Norby, P.

    1989-01-01

    Lithium insertion and deinsertion reactions have been carried out with LiCr3O8, NaCr3O8, and KCr3O8 chemically andelectrochemically at room temperature and at 125°C. The electrochemical experiments were performed with a nonaqueousliquid electrolyte at room temperature and with a polymer electroly...... is close to 4Li/NaCr3O8 and 1.3Li/KCr3O8.Lithium ion diffusion coefficients are similar for the two compounds in the comparable composition range.Thermally, the fully lithiated compounds appear to be as stable as the pristine materials.......Lithium insertion and deinsertion reactions have been carried out with LiCr3O8, NaCr3O8, and KCr3O8 chemically andelectrochemically at room temperature and at 125°C. The electrochemical experiments were performed with a nonaqueousliquid electrolyte at room temperature and with a polymer electrolyte....... At elevated temperatures, the isostructural compounds NaCr3O8 and KCr3O8 are able to accommodate morethan 4Li/MCr3O8. During this process, minor structural changes are observed. At room temperature, NaCr3O8 and KCr3O8also accommodate Li topotactically, but the maximum number of Li inserted per formula...

  3. 15 CFR 23.6 - Definitions.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Definitions. 23.6 Section 23.6 Commerce and Foreign Trade Office of the Secretary of Commerce USE OF PENALTY MAIL IN THE LOCATION AND... entities outside the Office of the Secretary charged with carrying out specified substantive functions (i.e...

  4. Growth, structure, Hirshfeld surface and spectroscopic properties of 2-amino-4-hydroxy-6-methylpyrimidinium-2,3-pyrazinedicorboxylate single crystal

    Science.gov (United States)

    Faizan, Mohd; Alam, Mohammad Jane; Afroz, Ziya; Rodrigues, Vítor Hugo Nunes; Ahmad, Shabbir

    2018-03-01

    The present work is focused on the crystal structure, vibrational spectroscopy and DFT calculations of hydrogen bonded 2,3-pyrazinedicorboxylic acid and 2-amino-4-hydroxy-6-methylpyrimidine (PDCA-.AHMP+) crystal. The crystal structure has been determined using single crystal X-ray diffraction analysis which shows that the crystal belongs to monoclinic space group P21/n. The PDCA-.AHMP+ crystal has been characterized by FTIR, FT-Raman and FT-NMR spectroscopic techniques. The FTIR and FT-Raman spectra of the complex have unique spectroscopic feature as compared with those of the starting material to confirm salt formation. The theoretical vibrational studies have been performed to understand the modes of the vibrations of asymmetric unit of the complex by DFT methods. Hirschfeld surface and 2D fingerprint plots analyses were carried out to investigate the intermolecular interactions and its contribution in the building of PDCA-.AHMP+ crystal. The experimental and simulated 13C and 1H NMR studies have assisted in structural analysis of PDCA-.AHMP+ crystal. The electronic spectroscopic properties of the complex were explored by the experimental as well as theoretical electronic spectra simulated using TD-DFT/IEF-PCM method at B3LYP/6-311++G (d,p) level of theory. In addition, frontier molecular orbitals, molecular electrostatic potential map (MEP) and nonlinear optical (NLO) properties using DFT method have been also presented.

  5. Investigation on cored-eutectic structure in Ni60/WC composite coatings fabricated by wide-band laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Qunshuang, E-mail: maqunshuang@126.com; Li, Yajiang, E-mail: yajli@sdu.edu.cn; Wang, Juan, E-mail: jwang@sdu.edu.cn; Liu, Kun, E-mail: liu_kun@163.com

    2015-10-05

    Highlights: • Perfect composite coatings were fabricated using wide-band laser cladding. • Special cored-eutectic structure was synthesized in Ni60/WC composite coatings. • Cored-eutectic consists of hard carbide compounds and fine lamellar eutectic of M{sub 23}C{sub 6} carbides and γ-Ni(Fe). • Wear resistance of coating layer was significantly improved due to precipitation of M{sub 23}C{sub 6} carbides. - Abstract: Ni60 composite coatings reinforced with WC particles were fabricated on the surface of Q550 steel using LDF4000-100 fiber laser device. The wide-band laser and circular beam laser used in laser cladding were obtained by optical lens. Microstructure, elemental distribution, phase constitution and wear properties of different composite coatings were investigated. The results showed that WC particles were partly dissolved under the effect of wide-band fiber laser irradiation. A special cored-eutectic structure was synthesized due to dissolution of WC particles. According to EDS and XRD results, the inside cores were confirmed as carbides of M{sub 23}C{sub 6} enriched in Cr, W and Fe. These complex carbides were primarily separated out in the molten metal when solidification started. Eutectic structure composed of M{sub 23}C{sub 6} carbides and γ-Ni(Fe) grew around carbides when cooling. Element content of Cr and W is lower at the bottom of cladding layer. In consequence, the eutectic structure formed in this region did not have inside carbides. The coatings made by circular laser beam were composed of dendritic matrix and interdendritic eutectic carbides, lacking of block carbides. Compared to coatings made by circular laser spot, the cored-eutectic structure formed in wide-band coatings had advantages of well-distribution and tight binding with matrix. The uniform power density and energy distribution and the weak liquid convection in molten pool lead to the unique microstructure evolution in composite coatings made by wide-band laser

  6. Binding properties of Clostridium botulinum type C progenitor toxin to mucins.

    Science.gov (United States)

    Nakamura, Toshio; Takada, Noriko; Tonozuka, Takashi; Sakano, Yoshiyuki; Oguma, Keiji; Nishikawa, Atsushi

    2007-04-01

    It has been reported that Clostridium botulinum type C 16S progenitor toxin (C16S toxin) first binds to the sialic acid on the cell surface of mucin before invading cells [A. Nishikawa, N. Uotsu, H. Arimitsu, J.C. Lee, Y. Miura, Y. Fujinaga, H. Nakada, T. Watanabe, T. Ohyama, Y. Sakano, K. Oguma, The receptor and transporter for internalization of Clostridium botulinum type C progenitor toxin into HT-29 cells, Biochem. Biophys. Res. Commun. 319 (2004) 327-333]. In this study we investigated the binding properties of the C16S toxin to glycoproteins. Although the toxin bound to membrane blotted mucin derived from the bovine submaxillary gland (BSM), which contains a lot of sialyl oligosaccharides, it did not bind to neuraminidase-treated BSM. The binding of the toxin to BSM was inhibited by N-acetylneuraminic acid, N-glycolylneuraminic acid, and sialyl oligosaccharides strongly, but was not inhibited by neutral oligosaccharides. Both sialyl alpha2-3 lactose and sialyl alpha2-6 lactose prevented binding similarly. On the other hand, the toxin also bound well to porcine gastric mucin. In this case, neutral oligosaccharides might play an important role as ligand, since galactose and lactose inhibited binding. These results suggest that the toxin is capable of recognizing a wide variety of oligosaccharide structures.

  7. Hot corrosion behavior of Ni-Cr-W-C alloys in impure helium gas

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1976-01-01

    Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995% helium gas at 1000 0 C, comparing with that behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure helium gas usually causes selective oxidation of these elements and the growth of oxide whiskers on the surface of specimen at elevated temperature. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by addition of Mn and Si, providing tough spinel type oxide film on the surface and 'Keyes' on the oxide-matrix interface respectively. The amount and the morphology of the oxide whiskers depended on Si and Mn content. More than 0.29% of Si content without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changed the whiskers to thicker ones of spinel type oxide (MnCr 2 O 1 ) with rough surface. On the basis of these results, the optimum content of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack and the spalling of oxide film was discussed. (auth.)

  8. Doping effects on structural and magnetic properties of Heusler alloys Fe2Cr1-xCoxSi

    Science.gov (United States)

    Liu, Yifan; Ren, Lizhu; Zheng, Yuhong; He, Shikun; Liu, Yang; Yang, Ping; Yang, Hyunsoo; Teo, Kie Leong

    2018-05-01

    In this work, 30nm Fe2Cr1-xCoxSi (FCCS) magnetic films were deposited on Cr buffered MgO (100) substrates by sputtering. Fe2Cr0.5Co0.5Si exhibits the largest magnetization and optimal ordered L21 cubic structure at in-situ annealing temperature (Tia) of 450°C. The Co composition dependence of crystalline structures, surface morphology, defects, lattice distortions and their correlation with the magnetic properties are analyzed in detail. The Co-doped samples show in-plane M-H loops with magnetic squareness ratio of 1 and increasing anisotropy energy density with Co composition. Appropriate Co doping composition promotes L21 phase but higher Co composition converts L21 to B2 phase. Doping effect and lattice mismatch both are proved to increase the defect density. In addition, distortions of the FCCS lattice are found to be approximately linear with Co composition. The largest lattice distortion (c/a) is 0.969 for Fe2Cr0.25Co0.75Si and the smallest is 0.983 for Fe2CrSi. Our analyses suggest that these tetragonal distortions mainly induced by an elastic stress from Cr buffer account for the large in-plane anisotropy energy. This work paves the way for further tailoring the magnetic and structural properties of quaternary Heusler alloys.

  9. Culture Optimization and Amino Acid Composition of Cr-Enriched Mycelia of Pleurotus cornucopiae SD-01

    Directory of Open Access Journals (Sweden)

    Fan-Yun Meng

    2010-01-01

    Full Text Available Chromium(III is an essential trace element for humans and animals. Pleutorus cornucopiae SD-01 is a nutritional and functional mushroom containing many kinds of bioactive ingredients. The aims of this work are to optimize the conditions of P. cornucopiae SD-01 cultivation with Cr enrichment in submerged culture by determining the dry cell mass, Cr content in mycelia and the rate of Cr enrichment, and to analyze the amino acid composition of Cr-enriched mycelia. The optimal medium contained (in g/L: potato 200, sucrose 25, yeast extract 4, KH2PO4 1 and MgSO4·7H2O 1. The optimum parameters of liquid culture were temperature 25 °C, cultivation time 6 days, the volume of the medium 100 mL, rotation speed 160 rpm and initial pH=6.5. Under the optimized conditions, the values of the dry cell mass, Cr content in mycelia and the rate of Cr enrichment were (6.63±0.35 g/L, (3670±211 μg/g and (12.15±1.01 % respectively, which were by (23.23±1.22, (18.19±1.06 and (45.68±2.67 % respectively, higher than those in the control. Chromium(III in Cr-enriched mycelia was mainly combined with protein and polysaccharide. The contents of total amino acids and essential amino acids in Cr-enriched mycelia were increased by (31.25±0.58 and (44.26±0.76 %, respectively.

  10. Quasicrystalline and crystalline precipitation during isothermal tempering in a 12Cr-9Ni-4Mo maraging stainless steel

    International Nuclear Information System (INIS)

    Liu, P.; Stigenberg, A.H.; Nilsson, J.O.

    1995-01-01

    A thorough microstructural investigation has been performed on a high strength maraging steel of the type 12%Cr-9%Ni-4%Mo-2%Cu-1%Ti. The major precipitate formed during isothermal aging at 475 C is a quasicrystalline phase possessing icosahedral symmetry termed R'-phase with a typical chemical composition of 48%Mo-33%Fe-13%Cr-2%Ni-4%Si. At 550 C the major precipitate is trigonal R-phase with a typical composition of 45%Mo-31%Fe-18%Cr-4%Ni-2%Si. At 550 C also Laves phase with a composition of 48%Mo-35%Fe-13%Cr-2%Ni-2%Si could be observed. At both 475 and 550 C an ordered phase termed L-phase precipitated. This minority phase has an ordered face centered cubic (f.c.c.) structure of type L1 0 . Its composition is typically 9%Fe-4%Cr-52%Ni-15%Mo.-16%Ti-4%Al. R'-phase formed at 475 C transformed to R-phase and Laves phase during aging at 550 C. In an analogous manner, R-phase and Laves phase formed at 550 C transformed to R'-phase during subsequent aging at 475 C. This transformation was rationalized by a strong similarity in crystal structure between quasicrystalline R'-phase of icosahedral symmetry and Frank-Kasper phases such as R-phase and Laves phase

  11. New WIMS library generation from ENDF/B6 and effect of resonance group structure on cell parameters

    International Nuclear Information System (INIS)

    Pazirandeh, Ali; Tabesh, Alireza

    2002-01-01

    Due to inaccessibility to NJOY, steps were taken to create WIMS library, which can be extracted from ENDF/B6 without using NJOY. In addition to using preprocessing codes few programs were written to calculate integral resonance, slowing down power per unit lethargy, potential scattering, and differential scattering cross section, scattering matrices. For neutrons with energy above 4 eV, isotropic elastic scattering was assumed. For neutrons below 4 eV the free gas model was used, except for light elements, which tabulated values of S(α,β) in ENDF/B6 used. The Goldstein-Cohen factors are taken from WIMKAL88.Lib. The integral resonance with self absorption per unit lethargy was obtained from GROUPIE output. The P 1 scattering matrices are calculated only for four elements, namely H, D, C and O at 300 K. In order to examine the created libraries, k eff , δ 28 , ρ 28 , ρ 25 and CR are calculated using new WIMS library, WIMKAL88.Lib and NEA329.Lib. The results showed general agreement. The controversial issue of WIMS library group structure, particularly in resonance region has raised the question of whether the number of resonance group i.e., 13 is optimized. We generated different WIMS libraries consisting of 5, 8, 13, 18 and 23 resonance groups. The main aim was to examine the effect to resonance group structure on calculated core parameters, mainly, k eff , δ 28 , ρ 28 , ρ 25 and CR. These parameters are also calculated and compared with those obtained using WIMKAL88, and NEA329 libraries. (author)

  12. Interaction of tantalum, chromium, and phosphorus at 1070 K: Phase diagram and structural chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Lomnytska, Ya. [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Babizhetskyy, V., E-mail: v.babizhetskyy@googlemail.com [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Oliynyk, A. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Toma, O. [Laboratory MOLTECH – Anjou, UMR-CNRS 6200, University of Angers, 49045 Angers (France); Dzevenko, M. [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Mar, A. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

    2016-03-15

    Solid-state phase equilibria have been established in the Ta–Cr–P system in the region of 0–67 at% P at 1070 K through powder X-ray diffraction analysis. Mutual substitution of Ta and Cr in binary phosphides gives rise to significant homogeneity ranges in Ta{sub 1.00–0.66}Cr{sub 0–0.34}P (NbAs-type; a=3.332(3)–3.1366(3) Å, c=11.386(4)–11.364(2) Å), Ta{sub 3.0–2.1}Cr{sub 0–0.9}P (Ti{sub 3}P-type, a=10.156(2)–9.9992(2) Å, c=5.015(1)–4.956(2) Å), and Cr{sub 3.0–2.4}Ta{sub 0–0.6}P (Ni{sub 3}P-type, a=9.186(5)–9.217(4) Å, c=4.557(3)–4.5911(3) Å). A limited homogeneity range is found in the ternary phase Ta{sub 1.0–0.8}Cr{sub 1.0–1.2}P (TiNiSi-type, a=6.2344(5)–6.141(2) Å, b=3.5034(3)–3.3769(6) Å, c=7.3769(6)–7.357(2) Å). The OsGe{sub 2}-type structures (space group C2/m) of a new P-rich compound, Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} (a=8.8586(3) Å, b=3.2670(2) Å, c=7.4871(2) Å, β=119.315(2)°) as well as of the Ti-containing analogue Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} (a=8.8592(5) Å, b=3.2663(3) Å, c=7.4870(5) Å, β=119.309(2)°) were refined from powder X-ray diffraction data. - Graphical abstract: Solid-state phase equilibria have been established in the Ta–Cr–P system in the region of 0–67 at% P at 1070 K through powder X-ray diffraction analysis. Mutual substitution of Ta and Cr in binary phosphides gives rise to significant homogeneity ranges in Ta{sub 1.00–0.66}Cr{sub 0–0.34}P, Ta{sub 3.0–2.1}Cr{sub 0–0.9}P, and Cr{sub 3.0–2.4}Ta{sub 0–0.6}P. A limited homogeneity range is found in the ternary phase Ta{sub 1.0–0.8}Cr{sub 1.0–1.2}P. The OsGe{sub 2}-type structures of a new P-rich compound, Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} as well as of the Ti-containing analogue Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} were establish from powder X-ray diffraction data. No homogeneity ranges for binary compounds Cr{sub 12}P{sub 7}, Cr{sub 2}P, Ta{sub 5}P{sub 3} were detected. - Highlights:

  13. Isotope Effects in the Bonds of beta-CrOOH and beta-CrOOD

    DEFF Research Database (Denmark)

    Nørlund Christensen, A.; Hansen, P.; Lehmann, M. S.

    1976-01-01

    Samples of orthorhombic chromium oxide hydroxide, beta -CrOOH, and the deuterated compound, beta -CrOOD, were prepared hydrothermally. The crystal structures were determined by powder profile refinement technique using neutron diffraction data. Unit cells are: beta -CrOOH: a equals 4. 862(2) A, b...... equals 4. 298(a) A, c equals 2. 995(1) A; beta -CrOOD: a equals 4. 873(5) A, b equals 4. 332(7) A, c equals 2. 963(2) A, with Z equals 2. The space group is P2//1nm or Pnnm....

  14. Effect of the thermal ageing on the tensile and impact properties of a 18%Cr ODS ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Rouffié, A.L., E-mail: anne-laure.rouffie@cea.fr [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Mines ParisTech, Centre des Matériaux P.M. Fourt, UMR CNRS 7633, BP 87, 91003 Evry (France); Crépin, J.; Sennour, M. [Mines ParisTech, Centre des Matériaux P.M. Fourt, UMR CNRS 7633, BP 87, 91003 Evry (France); Tanguy, B. [CEA, DEN, DANS, DMN, SEMI, Bât 625, F-91191 Gif-sur-Yvette (France); Pineau, A. [Mines ParisTech, Centre des Matériaux P.M. Fourt, UMR CNRS 7633, BP 87, 91003 Evry (France); Hamon, D.; Wident, P.; Vincent, S. [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Garat, V. [AREVA NP, 10 rue J. Récamier, 69006 Lyon (France); Fournier, B. [Manoir Industries – Petrochem and Nuclear, Metallurgy Dpt., 12 rue des Ardennes, BP 8401 Pitres, 27108 Val de Reuil Cedex (France)

    2014-02-01

    The effects of the thermal ageing at 400 °C, 500 °C and 600 °C during 5000 h on the mechanical properties of a 18%Cr ODS ferritic steel are investigated. A hardening effect is observed after ageing at 400 °C and 500 °C, probably due to the presence of chromium rich α′ particles as suggested by the literature. The impact resistance and the ductility of the material are strongly lowered by the ageing at 600 °C. This embrittlement is characterized on the fracture surfaces by the presence of cleavage facets on the whole range of testing temperatures. The intermetallic σ phase is found to be responsible for the occurrence of cleavage fracture on the material aged at 600 °C, and thus for the significant embrittlement of this material. M{sub 23}C{sub 6} carbides are also observed before and after thermal ageing. The lattice parameters of the σ phase and the M{sub 23}C{sub 6} carbides observed in this 18%Cr ODS steel aged at 600 °C during 5000 h are measured.

  15. Experimental and numerical analysis of the static and dynamic crack growth resistance behaviour of structural steels in the temperature range from 20 C to 350 C

    International Nuclear Information System (INIS)

    Aurich, D.; Gerwien, P.; Huenecke, J.; Klingbeil, D.; Krafka, H.; Kuenecke, G.; Ohm, K.; Veith, H.; Wossidlo, P.; Haecker, R.

    1998-01-01

    The crack growth resistance behaviour of the steels StE 460 and 22NiMoCr3-7 was determined in the temperature range from 23 C to 350 C by means of C(T), M(T), and ISO-V specimens tested under quasistatic and dynamic loads. The Russian steel 15Ch2NMFA-A was tested at room temperature and 50 C. In the steels StE 460 and 22 NiMoCr3-7, the minimum crack growth resistance is observed at about 250 C, with measured values always being higher for the latter steel type. The crack growth resistance behaviour of the tested materials correlates with the behaviour of flow curve, yield strength, and notch impact toughness as a function of temperature. Impact tests of ISO-V specimens give higher crack resistance values than quasistatic load tests, and the temperature dependence is significantly lower than those of specimens tested under static loads. A metallurgical analysis of the materials shows the causes of the dissimilar behaviour. The stretching zones determined for the C(T) specimen correspond to the toughness of the steels examined, and they are not much influenced by the temperature. The numerical analysis using damaging models for simulation of ductile crack growth is reported for all specimen types and two different temperatures each. (orig./CB) [de

  16. K4Nb6O17·4.5H2O: A novel dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III)

    International Nuclear Information System (INIS)

    Ma, Yuli; Liu, Xiaoqing; Li, Yang; Su, Yiguo; Chai, Zhanli; Wang, Xiaojing

    2014-01-01

    Graphical abstract: A well crystalline K 4 Nb 6 O 17 ·4.5H 2 O with a wide layer spacing possesses an excellent disposal performance for chromium species of Cr(VI) and Cr(III) as well as the superior recyclability due to its high stability and convenient regeneration process. - Highlights: • A nano-sheet K 4 Nb 6 O 17 ·4.5H 2 O with a large layer spacing was synthesized. • K 4 Nb 6 O 17 ·4.5H 2 O showed a superior photoreduction of Cr(VI) in an acidic solution. • The sample showed a high adsorption capacity of Cr(III) in a near neutral solution. • K 4 Nb 6 O 17 ·4.5H 2 O regenerated conveniently by immersing in a KOH solution. • A complete removal of chromium species was retained after recycling five times. - Abstract: A series of orthorhombic phase K 4 Nb 6 O 17 ·4.5H 2 O was synthesized via a hydrothermal approach. When presented in an acidic pH range, K 4 Nb 6 O 17 ·4.5H 2 O showed a strong ability in quick reduction from Cr(VI) to Cr(III). The resulted Cr(III) ions were removed by an effective adsorption through simply adjusting the solution pH from strong acidity to near neutrality, owing to the sample's unique nano-sheet structure with a wide layer spacing. The Cr(III) ions adsorbed onto samples were released again for reusing by eluting with 1 mol L −1 HCl solution, and K 4 Nb 6 O 17 ·4.5H 2 O regenerated by immersing in a KOH solution. The reduction efficiency of Cr(VI) was still up to 98% after irradiation for 60 min, and the removal efficiency of Cr(III) ions was as high as 83% even after five cycles. Therefore, K 4 Nb 6 O 17 ·4.5H 2 O is clearly demonstrated to be an excellent dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III). The relevant materials reported herein might be found various environment-related applications

  17. Effects of hydrostatic pressure on spin-lattice coupling in two-dimensional ferromagnetic Cr2Ge2Te6

    Science.gov (United States)

    Sun, Y.; Xiao, R. C.; Lin, G. T.; Zhang, R. R.; Ling, L. S.; Ma, Z. W.; Luo, X.; Lu, W. J.; Sun, Y. P.; Sheng, Z. G.

    2018-02-01

    Spin-lattice coupling plays an important role in both formation and understanding of the magnetism in two-dimensional magnetic semiconductors (2DMS). In this paper, the steady pressure effects on the lattice structure, Raman resonances, and magnetization of a 2DMS Cr2Ge2Te6 have been studied by both experiments and first principles calculations. It is found that the bond length of Cr-Cr decreases, the angle of Cr-Te-Cr diverges from 90°, and the Raman modes Eg3 and Ag1 show an increase with the application of external pressure. Consequently, the magnetic phase transition temperature TC decreases from 66.6 K to 60.6 K (˜9%) as the pressure increases from 0 to 1 GPa. These pressure effects not only confirm the existence of strong spin-lattice coupling but also reveal the detailed information about the lattice deformation effect on the magnetic properties in such 2DMS, which would be a benefit for the further understanding and manipulation of the magnetism in 2D materials.

  18. Low and high cycle fatigue behaviour of steel-X6CRNI1811 (Type 304 SS) in air and flowing sodium

    International Nuclear Information System (INIS)

    Huthmann, H.; Jenner, G.

    Strain controlled LCF-tests were performed on X6CrNi1811 steel (Type 304 SS) in air and flowing sodium in a non-isothermal sodium loop. The results measured at 550 deg. C in an upstream position of the sodium loop show an increase in fatigue life in the strain range from about 1.5% to 0.4% for the base material in the as-received condition while the welded joints remain unaffected by the environment. The LCF-behaviour of base material specimens tested at 500 deg. C in a downstream position after a prior pre-exposure to sodium (4058 h, 500 deg. C) is also improved in comparison to parallel specimens tested in air with comparable thermal aging. Load controlled HCF-tests performed on X6CrNi1811 steel at 550 deg. C show a significant increase in fatigue life in the low cycle region (Nsub(f) 6 cycles) and a higher endurance limit for the base material in sodium but no influence of the environment is indicated for the welded joints. (author)

  19. Replacement of lumpy chrome ore by agglomerated ore concentrates and lowering of specific power consumption and improvement of Cr-yield by means of improved slag composition in the production of H.C. Ferrochrome

    International Nuclear Information System (INIS)

    Retelsdorf, H.J.; Fichte, R.; Breuer, F.; Zimmermann, H.

    1982-06-01

    Work on this project is finished, but further work on the use of Cr-ore briquettes seems necessary. It was the aim of the project to develop improved slag compositions for the FeCr 4-6% C-process resulting in higher Cr-yield and lower specific power consumption. Furthermore, replacement of lumpy ore in the charge by agglomerated Cr-ore-fines or concentrates in the form of pellets and briquettes was to be tested. Experimentals were performed in a 70 kW and a 300 kW arc furnace. Two different slag compositions were tested. The high-MgO slag type proved suitable. The specific power consumption and the Cr-yield depend to a large extent on the type of Cr-ore and on the agglomeration process. Cr-ore pellets can be used up to 65% in the ore charge but briquettes can be used only up to 25% to replace lumpy ores without causing higher Cr-losses in the slag. (orig.) [de

  20. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    CERN Document Server

    Bollini, C G; Giambiagi, M

    2001-01-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I sub r sub i sub n sub g values.

  1. Microstructure and Wear Resistance of TIG Remelted NiCrBSi Thick Coatings

    Directory of Open Access Journals (Sweden)

    Guo-lu Li

    2018-01-01

    Full Text Available The self-fluxing NiCrBSi coatings with 800 μm thickness were prepared on the surface of AISI1045 steel substrate by plasma spraying. And the remelted coating was obtained using by the tungsten inert gas (TIG arc process. The microstructure, surface roughness, hardness, phase composition, and wear resistance of the sprayed coating and remelted coating were systematically investigated. The results demonstrate that TIG remelted treatment can significantly eliminate the microscopic defects in thick coating and improve its density. The surface roughness (Ra of the remelted coating is only 18.9% of the sprayed coating. The hardness of the remelted coating is 26.8% higher than that of the sprayed coating. The main phases in the sprayed coating are changed from γ-Ni, Cr7C3, and Cr2B to γ-Ni, Cr23C6, CrB, Ni3B, and Fe3C. The wear mass loss of the remelted coating is only 17.1% of the sprayed coating. Therefore, a Ni-based thick coating with good wear resistance can be obtained by plasma spraying and remelted technique.

  2. High-statistics investigation of K/sup 0/K/sup -/ decay of A/sub 2 //sup -/ produced by 23-GeV/c pi /sup -/ on hydrogen

    CERN Document Server

    Margulies, M; Kramer, M A; Lindenbaum, S J; Love, W A; Ozaki, S; Platner, E D; Saulys, A C; Willen, E H

    1976-01-01

    Reports results of an experiment studying the reaction pi /sup -/p to K/sub s//sup 0/K/sup -/p at incident pion momenta of 22.4 and 23.9 GeV /c performed using the Brookhaven Mark 1 Spectrometer. Determines the A/sub 2//sup -/ mass spectrum in the t' regions 00.29 (GeV/c)/sup 2/. Observes no two-peak structure and finds that an overall CERN MMS dipole-type fit is rejected by 8 standard deviations. Shows that the differential cross section data are well fitted by Ate/sup bt/ with b equivalent to 7.0 (GeV/c)/sup -2/ and that the total cross sections for pi /sup -/p to A/sub 2//sup -/p are sigma =2.6+or-0.4 mu b and 2.5+or-0.4 mu b at 22.4 and 23.9 GeV/c respectively. (19 refs).

  3. Isolation of a new anti-inflammatory 20, 21, 22, 23, 24, 25, 26, 27-octanorcucurbitacin-type triterpene from Ibervillea sonorae.

    Science.gov (United States)

    Jardón-Delgado, Angel; Magos-Guerrero, Gil Alfonso; Martínez-Vázquez, Mariano

    2014-01-01

    A new cucurbitane-type triterpene, 20, 21, 22, 23, 24, 25, 26, 27-octanorcucurbita-5-ene-3, 11, 16-trione (1), named kinoin D, was isolated from the roots of the medicinal plant Ibervillea sonorae, (wereque). The structure of 1 was established on the basis of extensive NMR and MS studies. In addition, the known kinoins B (3) and C (5) were isolated, as were 16alpha-20,25-trihydroxy-3alpha-(2-O-alpha-L-rhamnopyranosiyl-D-glucopyranosyloxy)-(10alpha)-cucurbit-5-en-11,22-dione (6), (22S)-16alpha,22-diacetoxy-20,25-dihydroxy-3alpha-[3,4,6-tri-O-acetyl-2-O-(2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl)-beta-glucopyranosyl]-(10alpha)-cucurbita-5,23t-dien-11-one (7) and 16alpha-acetoxy-20,25-dihydroxy-3alpha-[3,4,6-tri-O-acetyl-2-O-(2,3,4,-tri-O-acetyl-alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyl]-(10alpha)-cucurbita-5-ene-11,22-dione (8). Compound 1 exhibited anti-inflammatory activity in TPA-induced edema in mice.

  4. [The role of 2,3-DPG in nerve conduction of children with type 1 diabetes].

    Science.gov (United States)

    Pańkowska, Ewa; Szypowska, Agnieszka; Wysocka, Marta; Lipka, Maria

    2005-01-01

    Neuropathy is one of the chronic complications of diabetes, and it is uncommon in children and adolescents. It can be recognized in a short period after the onset of diabetes and not always is connected with poor metabolic control. Hypoxia is considered as one from greatest factors diabetic neuropathy and oxygen transport to tissue partially depends on the diphosphoglycerate (2,3 DPG) concentration. As showed recent clinical studies, its concentration in children with diabetes can be abnormal. To assess the role of 2,3 DPG in nerve conduction velocity, as well as qualification of risk factors. To study were included randomly selected 37 patients with diabetes type 1, average age 15.5+/-2.25 years, with a duration of diabetes of more than 5 years (av 9.64+/-1.95 years), treated with intensive insulin therapy (MDI and CSII), without metabolic acidosis pH - 7.35. The nerve conduction velocity was measured in the sensor and motor nerves. HbA1c and 2,3 DPG were assessed additionally. Changes in motor nerve conduction velocity were observed at 22 patients. Average value of HbA1c in the studied group was 8.22+/-1.2%, Average concentration of 2,3 DPG was 6.15+/-1.67 mmol/l (3.84-11 mmol/l), in group with nerve dysfunction was lower - 5.86+/-1.69 mmol/l vs. 6.38+/-1.67, but this difference was not statistically significant. The lower value of 2,3 DPG significantly correlated with abnormal results of electroneurography test, especially with motor and sensor nerve latency (r=-0.34, p=0.038; r=-0.4, p=0.013) but not correlated with HbA1c (r= -0,19;p= 0,25), age of patients (r=0.008; p=0.96) and diabetes duration (r=-0.16; p=0.31). Nerve dysfunction is common in children with type 1 diabetes despite metabolic control and duration of diabetes. 2,3 DPG can be an independent factor of diabetes neuropathy correlated with abnormal value of the nerve conduction test.

  5. Atomic scale characterization of white etching area and its adjacent matrix in a martensitic 100Cr6 bearing steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.J., E-mail: y.li@mpie.de [Max-Planck Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf D-40237 (Germany); Center for Interface-Dominated High Performance Materials, Ruhr-Universität Bochum, Bochum 44780 (Germany); Herbig, M.; Goto, S. [Max-Planck Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf D-40237 (Germany); Raabe, D., E-mail: d.raabe@mpie.de [Max-Planck Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf D-40237 (Germany)

    2017-01-15

    Atom probe tomography was employed to characterize the microstructure and C distribution in the white etching area (WEA) of a martensitic 100Cr6 bearing steel subjected to rolling contact fatigue. Different from its surrounding matrix where a plate-like martensitic structure prevails, the WEA exhibits equiaxed grains with a uniform grain size of about 10 nm. Significant C grain boundary enrichment (>7.5at.%) and an overall higher C concentration than the nominal value are observed in the WEA. These results suggest that the formation of WEA results from severe local plastic deformation that causes dissolution of carbides and the redistribution of C. - Highlights: •APT has been applied to characterize the microstructure of white etching area (WEA). •Quantitative analyses of C distribution indicate that carbides are dissolved on the WEA. •WEA contains equiaxed grains with a uniform grain size of 10 nm. •C segregation at grain boundaries stabilizes the nanosized grain structure. •Formation of WEA is explained by severe local plastic deformation introduced by cyclic contact loading.

  6. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  7. Oxidation of (Cr,Ti)_2AlC Compounds at 700-1000 °C for One Year in Air

    International Nuclear Information System (INIS)

    Lee, Jae Chun; Won, Sung Bin; Lee, Dong Bok; Park, Sang Whan

    2013-01-01

    (Cr,Ti)_2AlC compounds were synthesized by hot pressing, and oxidized at 700, 850, and 1000 °C in air for up to one year. They consisted of Ti-incorporated Cr_2AlC phase, Ti-rich phase, and Cr-rich phase. The formed scales divided into a uniform oxide layer and oxide nodules. The uniform oxide layer consisted primarily of a thin Al_2O_3 scale. The oxide nodules that originated from the Ti-rich phase consisted of TiO_2, which grew by both the outward diffusion of Ti"4+ ions and inward diffusion of O"2‒ ions. Chromium did not appreciably enter the oxide scale. Instead, it existed in the Ti-incorporated Cr_7C_3 sublayer after oxidation. (Cr,Ti)_2AlC compounds had good oxidation resistance, because of formation of the Al_2O_3 barrier layer.

  8. Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast.

    Science.gov (United States)

    Yang, Lu; Ciceri, Elena; Mester, Zoltán; Sturgeon, Ralph E

    2006-11-01

    A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95+/-2 degrees C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na2CO3 for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO3 and H2O2 was used for the determination of total Cr. Concentrations of 2,014+/-16, 1,952+/-103 and 76+/-48 mg kg-1 (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2+/-7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6+/-6.5% Cr(VI) reduced, n=3) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg-1 were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample.

  9. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Miao Yi [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Jiang, Xiaohong, E-mail: jxh0668@sina.com [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Piliptsou, D.G., E-mail: pdg_@mail.ru [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Zhuang, Yuzhao; Rogachev, A.V.; Rudenkov, A.S. [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Balmakou, A. [Faculty of Material Science and Technology, Slovak University of Technology, Trnava 91724 (Slovakia)

    2016-08-30

    Highlights: • Influence of the chromium interlayer on the structure and mechanical properties of a-C:Cr films. • Residual stress and wear of a-C:Cr and Cr/a-C varies due to their phase and surface morphology. • Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics. - Abstract: To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  10. The Zr-Ti-Cr system. Equilibria at 900 and 1100 C degrees

    International Nuclear Information System (INIS)

    Arico, Sergio F.; Gribaudo, Luis M.

    2003-01-01

    Main contributions to the knowledge of the ternary system Zr-Ti-Cr were published in the sixties. Stability domains of phases at temperatures between 500 and 1400 C degrees were there presented. Here, results related to the phase diagram at 900 and 1100 C degrees are informed. Three alloys with 40 at.% Cr and different Zr/Ti ratios and one more, richer in Cr, were elaborated. Specimens of the alloys were heat treated 1000 and 800 h at 900 and 1100 C degrees respectively. Phase characterizations were performed by optic metallography and X-ray diffraction analysis. Compositions were determined by microprobe. Alloys with 40 at.% Cr at both temperatures have biphasic equilibria between the intermetallic Laves phase AB 2 and the body-centered cubic solid solution containing principally zirconium and titanium. The Cr-rich alloy presents equilibrium of the AB 2 compound and the Cr-rich solid solution. Results of the present and previous works are used in order to propose new isothermal sections at 900 and 1100 C degrees. (author)

  11. Effect of long-term aging on microstructural stabilization and mechanical properties of 20Cr32Ni1Nb steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaofeng; Jia, Xiankai [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Gong, Jianming, E-mail: gongjm@njtech.edu.cn [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Key Lab of Design and Manufacture of Extreme Pressure Equipment, Jiangsu Province (China); Geng, Luyang; Tang, Jianqun; Jiang, Yong [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Key Lab of Design and Manufacture of Extreme Pressure Equipment, Jiangsu Province (China); Ni, Yingying; Yang, Xinyu [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China)

    2017-04-06

    The centrifugally cast 20Cr32Ni1Nb stainless steel aged at 950 ℃ from 200 h up to 5000 h was investigated on the mechanical properties and microstructural evolution using post-aged tensile tests, post-aged Charpy impact tests, Optical microscopy (OM) observations, and field emission-scanning electron microscopy (FE-SEM) examinations. Experimental results indicate that the as-cast microstructure of the steel typically consists of a supersaturated solid solution of austenite matrix with a network of interdendritic primary carbides (NbC and M{sub 23}C{sub 6}). During aging process, the growth and coarsening of NbC carbides and M{sub 23}C{sub 6} carbides as well as the transformation of NbC carbide into G phase take place. Meanwhile, the transformation of NbC into G phase releases C into the matrix during aging exposure. This released C tends to combine with Cr, and forms M{sub 23}C{sub 6} at the dendrite boundaries. Compared with a continuous reduction of the elongation in the whole aging period, the strength parameters (σ{sub ult} and σ{sub ys}) exhibit an initial increase followed by a continuous decrease with the aging time prolonged from 1000 h to 5000 h. Additionally, the variation of Charpy impact absorbed energy is relatively complex during aging process. The microstructural evolution during long-term aging process is consistent with the variation of mechanical properties.

  12. Modeling of chromium precipitation in Fe-Cr alloys

    International Nuclear Information System (INIS)

    Wallenius, J.; Olsson, P.; Lagerstedt, C.; Sandberg, N.; Chakarova, R.; Pontikis, V.

    2004-01-01

    We have implemented a set of Embedded Atom Method (EAM) potentials for simulation of Fe-Cr alloys. The functions for the pure elements were fitted to the respective elastic constants, vacancy formation energy, and thermal expansion coefficients. For Cr, properties of the paramagnetic state were applied, providing a positive Cauchy pressure and hence applicability of the EAM. By relaxing the requirement of reproducing the pressure-volume relation at short interaction distances, stability of the self-interstitial could be obtained. Our Fe-potential gives E lang110rang f -E lang111rang f =-0.23 eV. Mixed Fe-Cr pair potentials were fitted to the calculated mixing enthalpy of ferromagnetic Fe-Cr, which is negative for Cr concentrations below 6%. Simulation of thermal aging in Fe-Cr alloys using a potential fitted to the mixing enthalpy of Fe-20Cr exhibited pronounced Cr-precipitation for temperatures below 900 K, in agreement with the phase diagram. No such ordering was observed at any temperature using a potential fitted to the mixing enthalpy of Fe-5Cr. Applied to recoil cascade simulations the new potentials predict a smaller number of surviving defects than potentials found in the literature. We obtain a cascade efficiency of 0.135 NRT for damage energies in between 10 and 20 keV. An enhanced probability for Cr atoms to end up in defect structures is observed

  13. Creep-rupture-strength and creep-behaviour of stainless steel X6CrNi 1811 (DIN 1.4948)

    International Nuclear Information System (INIS)

    Solano, R.R.; Rivas, M. de las; Seith, B.; Schirra, M.

    1977-01-01

    The steel X6CrNi 1811 (DIN 1.4948) that will be used as a structure material for the german fast breder reactor SNR 300, was creep-tested in a temperature range of 550-650 deg C under base material condition as well as welded material condition. Tests are foreseen up to 30.000 hours with a continous measuring of the elongation. The test results up to about 4.000 hours is described. Taking into account the results of other programs carried out with the same material between 550 and 600 deg C at similar rupture time, were defined the stresses for the longterm test. The main point of this program (''Extrapolation Program'') lies in the knowledge of the creep-rupture-strength and creep behaviour of the structure materials up to 3.10 4 h at high temperature in order to extrapolate up to 10 5 h for reactor operating temperatures. (author) [es

  14. Creep-rupture-strength and creep-behaviour of stainless steel X6CrNi 1811 (DIN 1.4948)

    International Nuclear Information System (INIS)

    Solano, R.R.; Rivas, M. de las; Schirra, M.; Seith, B.

    1976-10-01

    The steel X6CrNi 1811 (DIN 1.4948) that will be used as a structure material for the German fast breeder reactor SNR 300 was creep-tested in a temperature range of 550-650 0 C under base material condition as well as welded material condition. Tests are foreseen up to 30.000 hours with a continuous measuring of the elongation. The present report describes the test results up to about 5.000 hours. Taking into account the results of other programs carried out with the same material between 550 and 600 0 C at similar rupture times, were defined the stresses for the long term tests. The main point of this program ('Extrapolation Program') lies in the knowledge of the creep time and creep behaviour of the structure materials up to 3 x 10 4 h at high temperature in order to extrapolate up to 10 5 h for operating temperatures. (orig.) [de

  15. CASPT2 study of inverse sandwich-type dinuclear Cr(I) and Fe(I) complexes of the dinitrogen molecule: significant differences in spin multiplicity and coordination structure between these two complexes.

    Science.gov (United States)

    Nakagaki, Masayuki; Sakaki, Shigeyoshi

    2014-02-20

    Inverse sandwich-type complexes (ISTCs), (μ-N2)[M(AIP)]2 (AIPH = (Z)-1-amino-3-imino-prop-1-ene; M = Cr and Fe), were investigated with the CASPT2 method. In the ISTC of Cr, the ground state takes a singlet spin multiplicity. However, the singlet to nonet spin states are close in energy to each other. The thermal average of effective magnetic moments (μeff) of these spin multiplicities is close to the experimental value. The η(2)-side-on coordination structure of N2 is calculated to be more stable than the η(1)-end-on coordination one. This is because the d-orbital of Cr forms a strong dπ-π* bonding interaction with the π* orbital of N2 in molecular plane. In the ISTC of Fe, on the other hand, the ground state takes a septet spin multiplicity, which agrees well with the experimentally reported μeff value. The η(1)-end-on structure of N2 is more stable than the η(2)-side-on structure. In the η(1)-end-on structure, two doubly occupied d-orbitals of Fe can form two dπ-π* bonding interactions. The negative spin density is found on the bridging N2 ligand in the Fe complex but is not in the Cr complex. All these interesting differences between ISTCs of Cr and Fe are discussed on the basis of the electronic structure and bonding nature.

  16. The Al-rich region of the Al-Mn-Ni alloy system. Part II. Phase equilibria at 620-1000 oC

    International Nuclear Information System (INIS)

    Balanetskyy, S.; Meisterernst, G.; Grushko, B.; Feuerbacher, M.

    2011-01-01

    Research highlights: → Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 deg. C by means of SEM, TEM, powder XRD and DTA. → Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P63/mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P63/m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P1121/a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (basecentered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. → The existence of a thermodynamically stable R-phase of stoichiometry Al 60 Mn 11 Ni 4 , reported earlier in literature, was not confirmed in the present study. - Abstract: Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 o C. Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P6 3 /mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P6 3 /m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P112 1 /a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (base-centered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. Their physicochemical behaviour in the Al-Mn-Ni alloy system was studied.

  17. 2,3-Diaminopyridinium 6-carboxypyridine-2-carboxylate

    Directory of Open Access Journals (Sweden)

    Mahsa Foroughian

    2011-12-01

    Full Text Available The asymmetric unit of the title proton-transfer compound, C5H8N3+·C7H4NO4−, consists of one mono-deprotonated pyridine-2,6-dicarboxylic acid as anion and one protonated 2,3-diaminopyridine as cation. The crystal packing shows extensive O—H...O, N—H...O and N—H...N hydrogen bonds. Thre are also several π–π interactions between the anions and also between the cations [centriod–centroid distances = 3.6634 (7, 3.7269 (7, 3.6705 (7 and 3.4164 (7 Å].

  18. Gradient microstructure and microhardness in a nitrided 18CrNiMo7-6 gear steel

    Science.gov (United States)

    Yang, R.; Wu, G. L.; Zhang, X.; Fu, W. T.; Huang, X.

    2017-07-01

    A commercial gear steel (18CrNiMo7-6) containing a tempered martensite structure was nitrided using a pressurized gas nitriding process under a pressure of 5 atm at 530 °C for 5 hours. The mechanical properties and microstructure of the nitrided sample were characterized by Vickers hardness measurements, X-ray diffraction, and backscatter electron imaging in a scanning electron microscope. A micro-hardness gradient was identified over a distance of 500 μm with hardness values of 900 HV at the top surface and 300 HV in the core. This micro-hardness gradient corresponds to a gradient in the microstructure that changes from a nitride compound layer at the top surface (∼ 20 μm thick) to a diffusion zone with a decreasing nitrogen concentration and precipitate density with distance from the surface, finally reaching the core matrix layer with a recovered martensite structure.

  19. Structure studies on actinides carboxylates. 6. Crystal structures of strontium uranyldimalonate trihydrate and barium uranyldimalonate trihydrate

    Energy Technology Data Exchange (ETDEWEB)

    Bombieri, G; Benetollo, F; Forsellini, E; Del Pra, A [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

    1980-01-01

    SrUO/sub 2/(C/sub 3/H/sub 2/O/sub 4/)/sub 2/.3H/sub 2/O and BaUO/sub 2/(C/sub 3/H/sub 2/O/sub 4/).3H/sub 2/O are isostructural. They crystallize in the orthorhombic system space group Pbca with eight molecules in cells of dimensions a = 16.729(8), b = 23.247(11) and c = 6.848(5) A and a = 17.063(9), b = 23.604(12) and c = 6.885(5) A, respectively. The structures were solved by the heavy-atom technique and refined with full-matrix least-squares to the R values of 0.043 and 0.046, respectively. The coordination geometry around the uranium atom is a pentagonal bipyramid with the malonates behaving as bidentate or terdentate ligands to the uranium atoms forming polymeric chains (UO/sub 2/(C/sub 3/H/sub 2/O/sub 4/)/sub 2/)sub(n)sup(2n-) parallel to c. The space between the uranyl dimalonate chains is occupied by the oxygen atoms belonging either to the water molecules or to the carboxylic groups. Each polyhedron shares two edges forming columns running in the same direction as the uranyl chains and connecting them four by four.

  20. Morphology, deformation, and defect structures of TiCr2 in Ti-Cr alloys

    International Nuclear Information System (INIS)

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1992-01-01

    The morphologies and defect structures of TiCr 2 in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr 2 . The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability

  1. Evaluation of weldments in Type 21-6-9 stainless steel for Compact Ignition Tokamak structural applications: Phase 1

    International Nuclear Information System (INIS)

    Alexander, D.J.; Goodwin, G.M.; Bloom, E.E.

    1991-06-01

    Primary design considerations for the Compact Ignition Tokamak toroidal field-coil cases are yield strength and toughness in the temperature range from 77 to 300 K. Type 21-6-9 stainless steel, also still known by its original Armco Steel Company trade name Nitronic 40, is the proposed alloy for this application. It has high yield strength and usually adequate base metal toughness, but weldments in thick sections have not been adequately characterized in terms of mechanical properties or hot-cracking propensity. In this study, weldability of the alloy in heavy sections and the mechanical properties of the resultant welds were investigated including tensile yield strength and Charpy V-notch toughness at 77 K and room temperature. Weldments were made in four different base metals using seven different filler metals. None of the weldments showed any indication of hot-cracking problems. All base metals, including weldment heat-affected zones, were found to have adequate strength and impact toughness at both test temperatures. Weld metals, on the other hand, except ERNiCr-3 and ENiCrFe-3 had impact toughnesses of less than 67 J at 77 K. Inconel 82 had an average weld metal impact toughness of over 135 J at 77 K, and although its strength at 77 K is less than that of type 21-6-9 base metal, at this point it is considered to be the first-choice filler metal. Phase 2 of this program will concentrate on composition refinement and process/procedure optimization for the generic ERNiCr-3 composition and will generate a design data base for base and weld metal, including tensile, fracture toughness, and crack growth rate data

  2. Manufacturing and High Heat Flux Testing of Brazed Flat-Type W/CuCrZr Plasma Facing Components

    Science.gov (United States)

    Lian, Youyun; Liu, Xiang; Feng, Fan; Chen, Lei; Cheng, Zhengkui; Wang, Jin; Chen, Jiming

    2016-02-01

    Water-cooled flat-type W/CuCrZr plasma facing components with an interlayer of oxygen-free copper (OFC) have been developed by using vacuum brazing route. The OFC layer for the accommodation of thermal stresses was cast onto the surface of W at a temperature range of 1150 °C-1200 °C in a vacuum furnace. The W/OFC cast tiles were vacuum brazed to a CuCrZr heat sink at 940 °C using the silver-free filler material CuMnSiCr. The microstructure, bonding strength, and high heat flux properties of the brazed W/CuCrZr joint samples were investigated. The W/Cu joint exhibits an average tensile strength of 134 MPa, which is about the same strength as pure annealed copper. High heat flux tests were performed in the electron beam facility EMS-60. Experimental results indicated that the brazed W/CuCrZr mock-up experienced screening tests of up to 15 MW/m2 and cyclic tests of 9 MW/m2 for 1000 cycles without visible damage. supported by National Natural Science Foundation of China (No. 11205049) and the National Magnetic Confinement Fusion Science Program of China (No. 2011GB110004)

  3. Monoclonal antibody OKB7, which identifies the 14OKd complement receptor type 2 (CR2), also identifies a 72Kd secreted fragment of CR2 that contains the C3d-binding site

    International Nuclear Information System (INIS)

    Myones, B.L.; Ross, G.D.

    1986-01-01

    CR 2 is a 140-145Kd glycoprotein expressed on B lymphocytes which binds both C3d and Epstein-Barr virus (EBV). OKB7, an IgG/sub 2a/ monoclonal antibody to CR 2 , blocks C3d and EBV binding, while HB-5, another monoclonal IgG/sub 2a/ anti-CR 2 , does not. A 72Kd C3d-binding glycoprotein (gp72), isolated from Raji cell media, was previously thought to be CR 2 because a polyclonal rabbit anti-gp72 inhibited EC3d rosettes. ELISA assay demonstrated that OKB7, but not HB-5, bound to purified gp72 fixed to microtiter wells. Insoluble and soluble gp72 blocked Raji cell uptake of 125 I-labeled OKB7, but not labeled anti-B2 or HB-5. Rabbit anti-gp72 immunoprecipitated bands at 140Kd and 72Kd from 125 I-labelled and solubilized B cell membranes. Culture media from Raji cells grown in the presence 3 H-labeled amino acids was sequentially immunoprecipitated by irrelevant antibody, OKB7, and HB-5. A single 72Kd radiolabeled band was demonstrated only with OKB7, and this was identical to that produced by the immunoprecipitation of 125 I-labeled gp72 with rabbit anti-gp72. Thus, OKB7, which identifies the 140Kd CR 2 molecule, also identifies a 72Kd shed fragment of CR 2 isolated from Raji cell media, which contains the C3d-binding site

  4. Role of Y in the oxidation resistance of CrAlYN coatings

    Science.gov (United States)

    Domínguez-Meister, S.; El Mrabet, S.; Escobar-Galindo, R.; Mariscal, A.; Jiménez de Haro, M. C.; Justo, A.; Brizuela, M.; Rojas, T. C.; Sánchez-López, J. C.

    2015-10-01

    CrAlYN coatings with different aluminum (4-12 at.%) and yttrium (2-5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr2N, and a more effective Fe and C blocking.

  5. Hot corrosion behavior of Ni-Cr-W-C alloys in impure He gas

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1977-01-01

    Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995%He gas at 1,000 0 C, in comparison with the behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure He gas usually causes selective oxidation of the elements described above and the growth of oxide whiskers on the surface of specimen at elevated temperatures. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by additions of Mn and Si, providing tough spinel type oxide film on the surface and 'keys' on the oxide-matrix interface respectively. The amount and morphology of the oxide whiskers depended on Si and Mn contents. Si of more than 0.29% without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changes the whiskers to thicker ones of spinel type oxide (MnCr 2 O 4 ) with rough surface. On the basis of these results, the optimum contents of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack, and the spalling of oxide film were discussed. (auth.)

  6. Spin flip at unelastic scattering of protons with energy near 6 NeV o 50Cr and 52Cr nuclei

    International Nuclear Information System (INIS)

    Andronov, Yu.F.; Chubinskij, O.V.; Vinogradov, L.I.; Ehl'-Ashri, F.I.; Gustova, L.V.

    1978-01-01

    Angular S(Q) and energy S(E) dependences spin flip probability S were studied in inelastic scattering of protons with excitation of the 2 1 + states of 50 Cr (Q=-0.782 MeV) and 52 Cr (Q=-1.434 MeV) energy range from 5.6 to 5.95 MeV. In particular, it is elucidated how strongly the behaviour of the spin flip probability depends upon the energy and angle of scattering at Esub(p) approximately 6 MeV for 50 Cr and 52 Cr. Thereby some additional information on specific features of the mechanism of inelastic sccattering by th nuclei is obtained. Measurements were carried out simultaneously in two proton detection channels at scattering angles differing by 30 deg. For targets use was made of self-sustaining enriched foils (87% 50 Cr and 99% 52 Cr). The angular and energy dependences of the spin flip probabilities for 50 Cr and 52 Cr are shown to be rather different: for 52 Cr has a relatively slight energy dependence in the range of a resonance observed in the excitation function; for 50 Cr the behaviour of S(E) undergoes sharp changes. The experimetnal values of S(Q) for sup(50, 52)Cr differ rather strongly from the calculations made on the statistical model and depend considerably upon the scattering angle

  7. Changes induced in a ZnS:Cr-based electroluminescent waveguide structure by intrinsic near-infrared laser radiation

    International Nuclear Information System (INIS)

    Vlasenko, N. A.; Oleksenko, P. F.; Mukhlyo, M. A.; Veligura, L. I.

    2013-01-01

    The causes of changes that occur in a thin-film electroluminescent metal-insulator-semiconductor-insulator-metal waveguide structure based on ZnS:Cr (Cr concentration of ∼4 × 10 20 cm −3 ) upon lasing (λ ≈ 2.6 μm) and that induce lasing cessation are studied. It is established that lasing ceases because of light-scattering inhomogeneities formed in the structure and, hence, optical losses enhance. The origin of the inhomogeneities and the causes of their formation are clarified by studying the surface topology and the crystal structure of constituent layers of the samples before and after lasing. The studies are performed by means of atomic force microscopy and X-ray radiography. It is shown that a substantial increase in the sizes of grains on the surface of the structure is the manifestation of changes induced in the ZnS:Cr film by recrystallization. Recrystallization is initiated by local heating by absorbed laser radiation in existing Cr clusters and quickened by a strong electric field (>1 MV cm −1 ). The changes observed in the ZnS:Cr film are as follows: the textured growth of ZnS crystallites, an increase in the content of Cr clusters, and the appearance of some CrS and a rather high ZnO content. Some ways for improving the stability of lasing in the ZnS:Cr-based waveguide structures are proposed

  8. Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 : in Search of Jahn–Teller Distorted Cr(II) Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Man-Rong; Deng, Zheng; Lapidus, Saul H.; Stephens, Peter W.; Segre, Carlo U.; Croft, Mark; Paria Sena, Robert; Hadermann, Joke; Walker, David; Greenblatt, Martha

    2016-10-17

    A novel 6H - type hexagonal perovskite Ba 3 (Cr 0.97(1) Te 0.03 (1 ) ) 2 TeO 9 was prepared at high pressure (6 GPa) and temperature ( 1 773 K). Both transmission electron microscopy and synchrotron powder x - ray diffraction data demonstrate that Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 crystallize s in P6 3 / mmc with face - shared (Cr 0.97(1) Te 0.03(1) )O 6 octahedral pairs interconnected with TeO 6 octahedra via corner - sharing. Structure analysis shows a mixed Cr 2+ /Cr 3+ valence state with ~ 10% Cr 2+ . The existence of Cr 2+ in Ba 3 (Cr 2+ 0.10(1) Cr 3+ 0.87(1) Te 6+ 0.03 ) 2 TeO 9 is further evidenced by x - ray absorption near edge spectr oscopy . Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy - state curvature at low temperature. In this work, the o ctahedral Cr 2+ O 6 component is stabilized in an oxide material for the first time ; the expected Jahn - Teller distortion of high - spin ( d 4 ) Cr 2+ is not found , which is attributed to the small proportion of Cr 2+ (~ 10%) and the face - sharing arrangement of CrO 6 octahedral pairs, that structu rally dis favor axial distortion.

  9. Identification of the c(10×6)-CN/Cu(001) surface structure

    KAUST Repository

    Shuttleworth, I.G.

    2014-01-01

    © 2014 Elsevier B.V. All rights reserved. A systematic survey of all possible c(10 x 6)-CN/Cu(0 0 1) structures has been performed using density functional theory (DFT). A group of four preferred structures is presented with one of the structures identified as optimal. An analysis of the bonding within the optimal structure has shown that a significant localisation of the surface Cu 4s bonds occurs in the saturated system.

  10. Identification of the c(10×6)-CN/Cu(001) surface structure

    KAUST Repository

    Shuttleworth, I.G.

    2014-12-01

    © 2014 Elsevier B.V. All rights reserved. A systematic survey of all possible c(10 x 6)-CN/Cu(0 0 1) structures has been performed using density functional theory (DFT). A group of four preferred structures is presented with one of the structures identified as optimal. An analysis of the bonding within the optimal structure has shown that a significant localisation of the surface Cu 4s bonds occurs in the saturated system.

  11. Results from CrIS/ATMS Obtained Using an "AIRS Version-6 Like" Retrieval Algorithm

    Science.gov (United States)

    Susskind, Joel; Kouvaris, Louis; Iredell, Lena; Blaisdell, John

    2015-01-01

    AIRS and CrIS Version-6.22 O3(p) and q(p) products are both superior to those of AIRS Version-6.Monthly mean August 2014 Version-6.22 AIRS and CrIS products agree reasonably well with OMPS, CERES, and witheach other. JPL plans to process AIRS and CrIS for many months and compare interannual differences. Updates to thecalibration of both CrIS and ATMS are still being finalized. We are also working with JPL to develop a joint AIRS/CrISlevel-1 to level-3 processing system using a still to be finalized Version-7 retrieval algorithm. The NASA Goddard DISCwill eventually use this system to reprocess all AIRS and recalibrated CrIS/ATMS. .

  12. Study of 13Cr-4Ni-(Mo (F6NM Steel Grade Heat Treatment for Maximum Hardness Control in Industrial Heats

    Directory of Open Access Journals (Sweden)

    Massimo De Sanctis

    2017-09-01

    Full Text Available The standard NACE MR0175 (ISO 15156 requires a maximum hardness value of 23 HRC for 13Cr-4Ni-(Mo steel grade for sour service, requiring a double tempering heat treatment at temperature in the range 648–691 °C for the first tempering and 593–621 °C for the second tempering. Difficulties in limiting alloy hardness after the tempering of forged mechanical components (F6NM are often faced. Variables affecting the thermal behavior of 13Cr-4Ni-(Mo during single and double tempering treatments have been studied by means of transmission electron microscopy (TEM observations, X-ray diffraction measurements, dilatometry, and thermo-mechanical simulations. It has been found that relatively low Ac1 temperatures in this alloy induce the formation of austenite phase above 600 °C during tempering, and that the formed, reverted austenite tends to be unstable upon cooling, thus contributing to the increase of final hardness via transformation to virgin martensite. Therefore, it is necessary to increase the Ac1 temperature as much as possible to allow the tempering of martensite at the temperature range required by NACE without the detrimental formation of virgin martensite upon final cooling. Attempts to do so have been carried out by reducing both carbon (<0.02% C and nitrogen (<100 ppm levels. Results obtained herein show final hardness below NACE limits without an unacceptable loss of mechanical strength.

  13. Atomic Structure of Type VI Contractile Sheath from Pseudomonas aeruginosa.

    Science.gov (United States)

    Salih, Osman; He, Shaoda; Planamente, Sara; Stach, Lasse; MacDonald, James T; Manoli, Eleni; Scheres, Sjors H W; Filloux, Alain; Freemont, Paul S

    2018-02-06

    Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures. Comparison with sheath structures from other contractile machines, including T4 phage and R-type pyocins, provides a better understanding of how these systems have conserved similar functions/mechanisms despite evolution. We used the P. aeruginosa R2 pyocin as a structural template to build an atomic model of the TssB1C1 sheath in its extended conformation, allowing us to propose a coiled-spring-like mechanism for T6SS sheath contraction. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Co-linear spin configurations in corundum-type structures

    International Nuclear Information System (INIS)

    Bertaut, F.

    1961-01-01

    The colinear magnetic configurations possible in corundum-type structures (α-Fe 2 O 3 ; Cr 2 O 3 ) are solutions of a matrices problem. Their regions of stability are bounded by inequality relationships between exchange integrals. (author) [fr

  15. Phase formation and microstructure evolution of arc ion deposited Cr2AlC coating after heat treatment

    International Nuclear Information System (INIS)

    Li, J.J.; Qian, Y.H.; Niu, D.; Zhang, M.M.; Liu, Z.M.; Li, M.S.

    2012-01-01

    Highlights: ► Cr 2 AlC coating was prepared by arc ion plating combined with post annealing. ► The coating deposited by arc ion plating without heating was amorphous. ► Amorphous coating transformed to crystalline Cr 2 AlC after annealing at 620 °C in Ar. - Abstract: Due to the excellent oxidation and hot corrosion resistance and matched thermal expansion coefficient to normal alloys, Cr 2 AlC has potential applications as high-temperature protective coating. In the present work, the preparation of Cr 2 AlC coating has been achieved through cathodic arc deposition method combined with heat post-treatment. It was found that the coating, deposited from Cr 2 AlC compound target in the unintentional heating condition, was amorphous. After annealing at 620 °C in Ar for 20 h, the amorphous Cr–Al–C coating happened to crystallize and transformed to crystalline Cr 2 AlC as the major phase. It is obvious that the formation temperature of Cr 2 AlC was decreased from about 1050 °C for sintered bulk to around 620 °C for the as-deposited coating, resulting from the homogeneous mixture of the Cr, Al and C at atomic level in the Cr–Al–C coating. Apart from crystalline Cr 2 AlC, the annealed coating also contained AlCr 2 and little Cr 7 C 3 . AlCr 2 formed due to the loss of C during deposition, and little Cr 7 C 3 always existed in the sintered Cr 2 AlC compound target as impurity phase.

  16. Spin-resolved photoelectron spectroscopy of Mn{sub 6}Cr single-molecule-magnets and of manganese compounds as reference layers

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas; Gryzia, Aaron; Dohmeier, Niklas; Mueller, Norbert; Brechling, Armin; Sacher, Marc; Heinzmann, Ulrich [Faculty of Physics, Bielefeld University (Germany); Hoeke, Veronika; Glaser, Thorsten [Faculty of Chemistry, Bielefeld University (Germany); Fonin, Mikhail; Ruediger, Ulrich [Department of Physics, University of Konstanz (Germany); Neumann, Manfred [Department of Physics, Osnabrueck University (Germany)

    2011-07-01

    The properties of the manganese-based single-molecule-magnet (SMM) Mn{sub 6}Cr are studied. This molecule exhibits a large spin ground state of S{sub T}=21/2. It contains six manganese centres arranged in two bowl-shaped Mn{sub 3}-triplesalen building blocks linked by a hexacyanochromate. The Mn{sub 6}Cr complex can be isolated with different counterions which compensate for its triply positive charge. The spin polarization of photoelectrons emitted from the manganese centres in Mn{sub 6}Cr SMM after resonant excitation with circularly polarized synchrotron radiation has been measured at selected energies corresponding to the prominent Mn L{sub 3}VV and L{sub 3}M{sub 2,3}V Auger peaks. Spin-resolved photoelectron spectra of the reference substances MnO, Mn{sub 2}O{sub 3} and Mn(II)acetate recorded after resonant excitation at the Mn-L{sub 3}-edge around 640eV are presented as well. The spin polarization value obtained from MnO at room temperature in the paramagnetic state is compared to XMCD measurements of Mn(II)-compounds at 5K and a magnetic field of 5T.

  17. Synthesis, structure and magnetic properties of crystallographically aligned CuCr_2Se_4 thin films

    International Nuclear Information System (INIS)

    Esters, Marco; Liebig, Andreas; Ditto, Jeffrey J.; Falmbigl, Matthias; Albrecht, Manfred; Johnson, David C.

    2016-01-01

    We report the low temperature synthesis of highly textured CuCr_2Se_4 thin films using the modulated elemental reactant (MER) method. The structure of CuCr_2Se_4 is determined for the first time in its thin film form and exhibits cell parameters that are smaller than found in bulk CuCr_2Se_4. X-ray diffraction and precession electron diffraction show a strong degree of crystallographic alignment of the crystallites, where the axis is oriented perpendicular to the substrate surface, while being rotationally disordered within the plane. Temperature and field dependent in-plane and out-of-plane magnetization measurements show that the film is ferromagnetic with a Curie temperature of 406 K CuCr_2Se_4 synthesized utilizing the MER method shows stronger magnetic anisotropy (effective anisotropy: 1.82 × 10"6 erg cm"−"3; shape anisotropy: 1.07 × 10"6 erg cm"−"3), with the easy axis lying out of plane, and a larger magnetic moment (6 μ_B/f.u.) than bulk CuCr_2Se_4. - Highlights: • Crystallographically aligned, phase pure CuCr_2Se_4 were synthesized. • The degree of alignment decreases with annealing time. • The films are ferromagnetic with the easy axis along the direction. • The magnetization is larger than bulk CuCr_2Se_4 or other CuCr_2Se_4 films made to date.

  18. The structural and electro-optical characteristics of AZO/Cr:Cu/AZO transparent conductive film

    International Nuclear Information System (INIS)

    Lin, Tien-Chai; Huang, Wen-Chang; Tsai, Fu-Chun

    2015-01-01

    A novel triple-layered transparent conductive film, AZO/Cr:Cu/AZO (ACCA), was presented in the paper. The structural and electro-optical properties of the ACCA film were discussed. The thickness of the middle metal layer was constant and those of the AZO layers were varied. The ACCA film shows an obvious ZnO (002) c-axis preferential growth. No diffraction peaks related to Cr and Cu were observed through x-ray diffraction analysis. The middle Cr:Cu layer showed a thickness of 8.16 nm with a continuous and amorphous structure by the observation of a high-resolution transmission electron microscopy (HR-TEM). For the electro-optical characteristic, a best figure of merit (FOM) value of 3.54 × 10 −3 Ω −1 with a corresponding transmittance of 85% was obtained at the thickness of 116 nm of ACCA film. The high FOM value of the film is due to the improvement of conductivity and small sacrifices of transparency. - Highlights: • A novel triple-layered transparent conductive film, AZO/Cr:Cu/AZO is developed. • Chromium is added to copper to reduce the oxidation–reduction reaction. • The film has a FOM of 3.54 × 10 −3 Ω −1 with a corresponding transmittance of 85%. • The Cr:Cu layer shows a continuous and amorphous structure

  19. The structural and electro-optical characteristics of AZO/Cr:Cu/AZO transparent conductive film

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tien-Chai [Department of Electrical Engineering, Kun Shan University, No. 195, Kun-Da Road, Yung-Kang Dist., Tainan 71003, Taiwan, ROC (China); Huang, Wen-Chang, E-mail: wchuang@mail.ksu.edu.tw [Department of Electro-Optical Engineering, Kun Shan University, No. 195, Kun-Da Road, Yung-Kang Dist., Tainan 71003, Taiwan, ROC (China); Tsai, Fu-Chun [Department of Electro-Optical Engineering, Kun Shan University, No. 195, Kun-Da Road, Yung-Kang Dist., Tainan 71003, Taiwan, ROC (China)

    2015-08-31

    A novel triple-layered transparent conductive film, AZO/Cr:Cu/AZO (ACCA), was presented in the paper. The structural and electro-optical properties of the ACCA film were discussed. The thickness of the middle metal layer was constant and those of the AZO layers were varied. The ACCA film shows an obvious ZnO (002) c-axis preferential growth. No diffraction peaks related to Cr and Cu were observed through x-ray diffraction analysis. The middle Cr:Cu layer showed a thickness of 8.16 nm with a continuous and amorphous structure by the observation of a high-resolution transmission electron microscopy (HR-TEM). For the electro-optical characteristic, a best figure of merit (FOM) value of 3.54 × 10{sup −3} Ω{sup −1} with a corresponding transmittance of 85% was obtained at the thickness of 116 nm of ACCA film. The high FOM value of the film is due to the improvement of conductivity and small sacrifices of transparency. - Highlights: • A novel triple-layered transparent conductive film, AZO/Cr:Cu/AZO is developed. • Chromium is added to copper to reduce the oxidation–reduction reaction. • The film has a FOM of 3.54 × 10{sup −3} Ω{sup −1} with a corresponding transmittance of 85%. • The Cr:Cu layer shows a continuous and amorphous structure.

  20. Preparation, Structure, and Dielectric and Magnetic Properties of SrFe2/3W1/3O3 Ceramics

    Science.gov (United States)

    Pavlenko, A. V.; Turik, A. V.; Shilkina, L. A.; Kubrin, S. P.; Rusalev, Yu. V.; Reznichenko, L. A.; Andryushina, I. N.

    2018-03-01

    Polycrystalline samples of SrFe2/3W1/3O3 (SFWO) ceramic were obtained by solid-phase reactions with subsequent sintering using conventional ceramic technology. X-ray diffraction analysis showed that at room temperature, the SFWO ceramic is single-phase and has a perovskite-type structure with tetragonal symmetry and parameters a = 3.941(9) Å, c = 3.955(6) Å, and c/a = 1.0035. In studying the magnetic properties and the Mössbauer effect in SFWO ceramics, it is found that the material is a ferrimagnet, and the iron ions are only in the valence state of Fe3+. It is suggested that in the temperature range of T = 150-210°C, a smeared phase transition from a cubic (paraelectric) phase to a tetragonal (ferroelectric) phase takes place in SFWO with decreasing temperature.

  1. Crystal structure and phase transitions in perovskite-like C(NH2)3SnCl3

    International Nuclear Information System (INIS)

    Szafranski, Marek; Stahl, Kenny

    2007-01-01

    X-ray single-crystal diffraction, high-temperature powder diffraction and differential thermal analysis at ambient and high pressure have been employed to study the crystal structure and phase transitions of guanidinium trichlorostannate, C(NH 2 ) 3 SnCl 3 . At 295 K the crystal structure is orthorhombic, space group Pbca, Z=8, a=7.7506(2) A, b=12.0958(4) A and c=17.8049(6) A, solved from single-crystal data. It is perovskite-like with distorted corner-linked SnCl 6 octahedra and with ordered guanidinium cations in the distorted cuboctahedral voids. At 400 K the structure shows a first-order order-disorder phase transition. The space group is changed to Pnma with Z=4, a=12.1552(2) A, b=8.8590(2) A and c=8.0175(1) A, solved from powder diffraction data and showing disordering of the guanidinium cations. At 419 K, the structure shows yet another first-order order-disorder transformation with disordering of the SnCl 3 - part. The space group symmetry is maintained as Pnma, with a=12.1786(2) A, b=8.8642(2) A and c=8.0821(2) A. The thermodynamic parameters of these transitions and the p-T phase diagram have been determined and described. - Graphical abstract: The perovskite-like crystals of C(NH 2 ) 3 SnCl 3 undergo two successive first-order phase transitions at 400 and 419 K, both accompanied by an essential order-disorder contribution. The p-T phase diagram exhibits a singular point at 219 MPa and 443 K

  2. The effects of some factors on the creep behavior of type 304 stainless steel

    International Nuclear Information System (INIS)

    Nakazawa, Takanori; Abo, Hideo

    1977-01-01

    The effects of some factors on the creep behavior of type 304 stainless steel have been studied, and relationships between the strength and the structures in the steel have been discussed. Main results obtained were as follows: (1) Creep strength and creep rupture strength at 550, 600, and 650 0 C increased with cold working rate up to 20%, but creep rupture elongation decreased. These facts were explained by the strengthening of matrix by dislocations which acted as precipitation sites of carbides during creep. (2) The steel was aged for up to 3000h at 550-700 0 C. Carbides precipitated on grain boundary and in the neighborhood of grain boundary. With long time or high temperature aging creep strength and creep rupture strength decreased, but creep rupture elongation increased. (3) Creep strength at 600 0 C was independent of the grain size. Initiation of crack was accelerated with growth of grains, and therefore the creep rupture strength and elongation became lower. (4) Creep strength of type 304 stainless steel stemed from uniformly distributed fine carbieds (Cr, Fe) 23 -C 6 which precipitated on dislocations during creep. (auth.)

  3. Radiation-resistant photostructure for Schottky diode based on Cr/In2Hg3Te6

    Directory of Open Access Journals (Sweden)

    Ashcheulov A. A.

    2016-05-01

    Full Text Available Ge, Si, InGaAs, GaInAsP photodiodes are used as optical radiation receivers and function in a spectral range of transparency of quartz fiberglass. For the optical systems operated in the increased radioactivity the photodetectors' application on In2Hg3Te6 crystal base characterized by a photosensitivity in the spectral range of 0,5-1,6 mm and also by increased radiation resistance to alpha, beta and gamma radiation is most acceptable. Schottky photodiode structure was designed on the base of this semiconductor formed by a modified floating zone recrystallization technique where the sedimentation effect was leveled. It consists of n-In2Hg3Te6 substrate and deposited by cathode sputtering Cr barrier layer of thickness within a range 10-11 nm choice of Cr is determined by its optimal optical, electric and adhesive features in high quality radiation-resistant photodiode structures manufacturing. Indium and nichrome are used as ohmic contacts. The barrier structures have the contact area of 1,13 mm2 with photo response of 0,6-1,6 mm at the maximal sensitivity 0,43 A/W on the wavelength l,55 mm. Reverse dark current of these structures do not exceed 4 mA at the bias of 1 V (T=295 K, and the potential barrier height is equal to 0,41 eV. The tests of radiation resistance of these structures demonstrated their ability to function at doses of 2⋅108 rem without evident parameters changes. This allows using them in practical aims in the conditions of high radiation.

  4. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    International Nuclear Information System (INIS)

    Teh, Geok Bee; Wong, Yat Choy; Tilley, Richard D.

    2011-01-01

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P6 3 /mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe 12 O 19 with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: → High annealing temperature produced M-type ferrite with higher oxygen vacancies. → Photoluminescence intensity is proportional to the existence of oxygen vacancies. → XRD data showed cell contraction well suited to the change of oxygen vacancies. → Shift in hysteresis loop due to defect-induced exchange bias was observed.

  5. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Teh, Geok Bee, E-mail: sharonteh2009@gmail.com [Division of Bioscience and Chemistry, School of Arts and Science, Tunku Abdul Rahman College, Jalan Genting Kelang, 53300 Kuala Lumpur (Malaysia); Wong, Yat Choy [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122 (Australia); Tilley, Richard D. [School of Chemical and Physical Sciences, MacDiarmid Institute of Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington (New Zealand)

    2011-09-15

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P6{sub 3}/mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe{sub 12}O{sub 19} with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: > High annealing temperature produced M-type ferrite with higher oxygen vacancies. > Photoluminescence intensity is proportional to the existence of oxygen vacancies. > XRD data showed cell contraction well suited to the change of oxygen vacancies. > Shift in hysteresis loop due to defect-induced exchange bias was observed.

  6. Ca2Cr0.5Ga1.5O5—An extremely redox-stable brownmillerite phase

    International Nuclear Information System (INIS)

    Luo, Kun; Amano Patino, Midori; Hayward, Michael A.

    2015-01-01

    Investigation of the Ca 2 Cr x Ga 2−x O 5 compositional series reveals a maximum chromium solubility of 25%. The most chromium rich composition, Ca 2 Cr 0.5 Ga 1.5 O 5 , adopts a brownmillerite-type anion deficient perovskite structure described in space group Pnma (a=5.368 Å, b=14.547 Å, c=5.593 Å). Neutron powder diffraction data reveals rigorous B-site cation order, with all of the tetrahedral coordination sites occupied exclusively by gallium and the octahedral coordination sites occupied by gallium or chromium. Annealing studies reveals Ca 2 Cr 0.5 Ga 1.5 O 5 is stable in both oxidizing (100% O 2 ) and reducing (5% H 2 in N 2 ) conditions up to 800 °C, suggesting it could find application as a stable host lattice for fuel cell electrodes or electrolytes with suitable doping to enhance catalytic behaviour and/or anionic conductivity. - Graphical abstract: Ca 2 Cr 0.5 Ga 1.5 O 5 , adopts a brownmillerite-type anion deficient perovskite structure yet it is stable in both oxidizing (100% O 2 ) and reducing (5% H 2 in N 2 ) conditions up to 800 °C. - Highlights: • Anion deficient oxide stable to both oxidation and reduction up to 800 °C. • Cation-ordered brownmillerite structure determined by powder neutron diffraction. • Low solubility of Cr 3+ in framework due to spherical d 3 electron configuration

  7. η6-Cycloparaphenylene transition metal complexes: synthesis, structure, photophysical properties, and application to the selective monofunctionalization of cycloparaphenylenes.

    Science.gov (United States)

    Kubota, Natsumi; Segawa, Yasutomo; Itami, Kenichiro

    2015-01-28

    The synthesis, structure, photophysical properties, and reactivity of cycloparaphenylenes (CPPs) coordinated to group 6 transition metal fragments are described. The η(6)-coordination of [9]CPP or [12]CPP with M(CO)6 (M = Cr, Mo, W) afforded the corresponding [n]CPP-M(CO)3 complexes (n = 9, 12; M = Cr, Mo, W). In the (1)H NMR spectra of these complexes, characteristic upfield-shifted singlet signals corresponding to the four hydrogen atoms attached to the coordinated C6H4 ring of the CPPs were observed at 5.4-5.9 ppm. The complex [9]CPP-Cr(CO)3 could be successfully isolated in spite of its instability. X-ray crystallographic analysis and computational studies of [9]CPP-Cr(CO)3 revealed that chromium-CPP coordination occurs at the convex surface of [9]CPP both in the solid state and in solution. TD-DFT calculations suggested that the emerging high-wavenumber absorption peak upon coordination of [9]CPP to Cr(CO)3 should be assigned to a weak HOMO-LUMO transition. Moreover, by using the complex [9]CPP-Cr(CO)3, a rapid and highly monoselective CPP functionalization has been achieved. The established one-pot method, consisting of complexation, deprotonation, nucleophilic substitution, and decomplexation steps, yielded silyl-, boryl-, and methoxycarbonyl-substituted CPPs in up to 93% yield relative to reacted starting material.

  8. Crystal structure and thermal behavior of KB3O6

    International Nuclear Information System (INIS)

    Bubnova, R.S.; Fundamenskij, V.S.; Filatov, S.K.; Polyakova, I.G.

    2004-01-01

    The structure of potassium triborate prepared in metastable state by crystallization from melt at ∼ 800 deg C was studied by the method of X-ray diffraction analysis. It was ascertained that KB 3 O 6 belongs to monoclinic crystal system, space group P2 1 /c, a = 9.319(1), b = 6.648(1), c = 21.094(2) A, β = 94.38(1) deg, Z = 12. The compound is referred to a new structural type. Anion of the structure is a single boron-oxygen frame formed by three independent rigid triborate rings of [B 3 O 5 ] - , each of them consisting of two BO 3 triangles and BO 4 tetrahedron. Phase transformations during KB 3 O 6 heating up to 800 deg C, as well as thermal expansion in the range of 20-650 deg C, were studied [ru

  9. Martensitic transformations, structure, and strengthness of processed high-nitrogen and high-carbon ferrous alloys

    Science.gov (United States)

    Kaputkina, L. M.; Prokoshkina, V. G.

    2003-10-01

    Structures and properties of metastable austenitic alloys Fe-18Cr-16Ni-I2Mn-(0.17 to 0. 50)N, Fe-18Cr-12Mn-(0.48 to 1.12)N, Fe-18Cr-(0.1 to 1.18)N, and Fe-(12 to 20)Ni-(0.6 to 1.3)C, Fe-(6 to 8)Mn-(0.6 to 1.0)C, Fe-(5 to 6)Cr-(4 to 5)Mn-(0.6 to 0.8)C, Fe-6Cr-(1.0 to 1.3)C resulting from martensitic transformations under cooling and cold deformation (CD), as well as following tempering processes, were studied by magnetometry, X-ray and electron microscopy analyses, hardness measurements and mechanical properties tests. Martensite with a b.c.t. lattice was formed in all alloys with M_s{>}-196^circC during cooling. Under CD transformations of γ{to}α, γ{to}\\varepsilon{to}α, or γ{to}\\varepsilon types were realized depending on the alloy composition. Carbon increased but nitrogen decreased stacking fault energy. Thus carbon assists α-martensite formation but nitrogen promotese. As CD level and/or concentration of carbon and nitrogen increase residual stresses resulting from the CD also increase. The martensitic transformation during CD can decrease the residual stresses. Kinetic of tempering of b.c.t. thermal martensite differs from those of CD-induced martensite. In the second case, deformation aging, texture, and residual stresses are more visible. The maximal strengthening under CD takes place in (Mn+N)-steels. (Cr+N) and (Cr+Mn+N)-steels are high-strength, non-magnetic and corrosion resistant and are easily hardened by a low level of plastic deformation.

  10. Magnetic and transport properties of Cu1.05Cr0.89 Mg0.05O2 and Cu0.96Cr0.95 Mg0.05Mn0.04O2 films

    International Nuclear Information System (INIS)

    Xu Qingyu; Schmidt, Heidemarie; Zhou Shengqiang; Potzger, Kay; Helm, Manfred; Hochmuth, Holger; Lorenz, Michael; Meinecke, Christoph; Grundmann, Marius

    2008-01-01

    We prepared conductive, polycrystalline or amorphous Cu 1.05 Cr 0.89 Mg 0.05 O 2 films on a-plane sapphire substrates by pulsed laser deposition under different O 2 partial pressure and substrate temperature. Hall measurements were performed to study the majority carrier type in these films. Polycrystalline Cu 1.05 Cr 0.89 Mg 0.05 O 2 is n-type conducting at 290 K, while in amorphous Cu 1.05 Cr 0.89 Mg 0.05 O 2 the type of majority charge carriers changes from electrons to holes at around 270 K. Interestingly, the structure has little influence on the magnetic properties of the films. A clear antiferromagnetic to paramagnetic transition was observed in both polycrystalline and amorphous Cu 1.05 Cr 0.89 Mg 0.05 O 2 films at 25 K. Similar electrical properties to Cu 1.05 Cr 0.89 Mg 0.05 O 2 film were observed for Cu 0.96 Cr 0.95 Mg 0.05 Mn 0.04 O 2 in dependence on the structure, while only paramagnetic without antiferromagnetic ordering was observed down to 5 K. Large negative magnetoresistance of 27% at 20 K was observed at 6 T in amorphous Cu 1.05 Cr 0.89 Mg 0.05 O 2 film

  11. Primary photoluminescence in as-neutron (electron) -irradiated n-type 6H-SiC

    International Nuclear Information System (INIS)

    Zhong, Z.Q.; Wu, D.X.; Gong, M.; Wang, O.; Shi, S.L.; Xu, S.J.; Chen, X.D.; Ling, C.C.; Fung, S.; Beling, C.D.; Brauer, G.; Anwand, W.; Skorupa, W.

    2006-01-01

    Low-temperature photoluminescence spectroscopy has revealed a series of features labeled S 1 , S 2 , S 3 in n-type 6H-SiC after neutron and electron irradiation. Thermal annealing studies showed that the defects S 1 , S 2 , S 3 disappeared at 500 deg. C. However, the well-known D 1 center was only detected for annealing temperatures over 700 deg. C. This experimental observation not only indicated that the defects S 1 , S 2 , S 3 were a set of primary defects and the D 1 center was a kind of secondary defect, but also showed that the D 1 center and the E 1 , E 2 observed using deep level transient spectroscopy might not be the same type of defects arising from the same physical origin

  12. Crystal structure of clathrates of Hofmann dma-type

    International Nuclear Information System (INIS)

    NIshikiori, Sh.; Ivamoto, T.

    1999-01-01

    Seven new clathrates Cd(DMA) 2 Ni(CN) 4 ·xG (x=1, G=aniline, 2,3-xylidine, 2,4-xylidine, 2,5-xylidine, 2,6-xylidine, 3,5-xylidine, and x=2, G=2,4,6-trimethylaniline) of Hofmann type are synthesized by amine substitution for dimethylamine (DMA). On the base of x-ray diffraction data it is shown that geometry of guest molecule in cage-like hollow determines the structure of the host and crystal structure of clathrates. Two-dimension metallocomplex of the host of studied clathrates is characterized by elastic folded structure appearing as a result of angular deformation of bond between Cd atoms and host cyanide bridge. Guest molecule orientation is fixed by hydrogen bond. Structural elasticity of the host complex directs to differences in crystal structure of clathrates formed and to considerable variety of incorporated guests [ru

  13. Transformation and Precipitation Kinetics in 30Cr10Ni Duplex Stainless Steel

    Science.gov (United States)

    Fazarinc, Matevz; Terčelj, Milan; Bombač, David; Kugler, Goran

    2010-09-01

    To improve the microstructure during casting, hot forming, and heat treatment of 30Cr10Ni duplex stainless steel, accurate data on the precipitation and transformation processes at high temperatures are needed. In this article, the precipitation and transformation processes at various aging times in the temperature range 873 K to 1573 K (600 °C to 1300 °C) were studied. The 30Cr10Ni ferrous alloy contains a relatively large amount of Cr, Ni, and C, which results in a complex microstructure. In addition to the ferrite, austenite, and sigma phase, the M23C6 and MC carbides were also observed in the microstructure. The precipitation of the sigma phase was observed after just 3 minutes of aging, and after 30 minutes of aging at approximately 1053 K (780 °C), its fraction exceeded 40 pct. An intensive austenite-to-ferrite transformation was observed above 1423 K (1150 °C). Optical microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD), as well as micro-indentation hardness, hardness, impact toughness, and tensile tests, were carried out to evaluate the obtained microstructures of aged samples.

  14. Hexagonal perovskites with cationic vacancies. 5. Structure determination on H-Ba/sub 2/Lusub(2/3)vacantsub(1/3)WO/sub 6/ - a novel rhombohedral stacking polytype with 18 layers

    Energy Technology Data Exchange (ETDEWEB)

    Wischert, W; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1979-01-01

    Compounds of type Ba/sub 2/Bsub(2/3)sup(III)vacantsub(1/3)Wsup(VI)O/sub 6/ with Bsup(III) = Gd-Lu, Y are polymorphic. They crystallize in a cubic 1:1 ordered perovskite structure and in a new rhombohedral perovskite stacking polytype of 18 L respectively. By intensity calculations out of the three possible stacking sequences (4)(2), (5)(1) and (3)1(1)1 (all space group R3m) the sequence (5)(1) can be selected. For H-Ba/sub 2/Lusub(2/3)vacant sub(1/3)WO/sub 6/ the refined R' factor is 14.1%. The structure contains groups of three octahedra connected with another by common faces which are linked with each other by three corner sharing octahedra. In the block of three face sharing octahedra the central octahedral lattice site is vacant, the two outer positions are occupied by tungsten atoms. According to this distribution a direct contact of occupied face sharing octahedra is absent.

  15. Intermediate temperature embrittlement of one new Ni-26W-6Cr based superalloy for molten salt reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Li [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Science, Beijing 100049 (China); Ye, Xiangxi [University of Chinese Academy of Science, Beijing 100049 (China); Cui, Chuanyong [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Huang, Hefei; Leng, Bin [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Zhijun, E-mail: lizhijun@sinap.ac.cn [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhou, Xingtai [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-06-21

    Ni-26W-6Cr based superalloy is considered a potential structure material for the molten salt reactors due to its high strength and good compatibility with the fluoride salt. In the present work, the temperature dependence of the tensile behavior of the alloy was studied by tensile tests in the temperature range of 25–850 °C. This alloy exhibited a good ductility at RT and 450 °C, a ductility minimum from 650 to 750 °C and an intermediate ductility at 850 °C. TEM and EBSD characterization was performed on specimens tested at three typical temperature points (RT, 650 °C and 850 °C) to determine the deformation and fracture mechanisms accounting for the intermediate temperature embrittlement. At RT, the grain boundaries can accommodate enough dislocations to provide compatibility of the sliding between adjacent grains, then M{sub 6}C carbides act as crack origins and cause the fracture. In case of 650 °C, the grain boundaries cannot withstand the local stress even if only a small number of dislocation pile-ups exist. The premature cracks at grain boundaries impede the development of plastic deformation from single slips to multiple ones and cause the low ductility. If tested at 850 °C, the fracture process is retarded by the dynamic recovery and local dynamic recrystallization at crack tips.

  16. Probing the magnetic moments of [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} single-molecule magnets—A cross comparison of XMCD and spin-resolved electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas, E-mail: helmstedt.andreas@gmail.com [Faculty of Physics, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld (Germany); Dohmeier, Niklas; Müller, Norbert; Gryzia, Aaron; Brechling, Armin; Heinzmann, Ulrich [Faculty of Physics, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld (Germany); Hoeke, Veronika; Krickemeyer, Erich; Glaser, Thorsten [Faculty of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld (Germany); Leicht, Philipp; Fonin, Mikhail [Fachbereich Physik, Universität Konstanz, Universitätsstr. 10, 78457 Konstanz (Germany); Tietze, Thomas [Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart (Germany); Joly, Loïc [Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS-Université de Strasbourg, BP 43, 23 rue du Loess, F-67034 Strasbourg Cedex 2 (France); Kuepper, Karsten [Institut für Festkörperphysik, Universität Ulm, 89069 Ulm (Germany)

    2015-01-15

    Highlights: • [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} single-molecule magnets are investigated. • XMCD and spin-resolved electron spectroscopy (SPES) results are compared. • A simple sum rule evaluation is performed for comparison. • Differences between SPES and XMCD results are discussed. • Influences of the magnetic field on the Mn L edge absorption are observed. - Abstract: Single-molecule magnets (SMM) of the [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} structural type prepared on Si and gold-coated glass substrates have been investigated by spin-resolved electron spectroscopy (SPES) and X-ray magnetic circular dichroism (XMCD) at the Mn L{sub 3,2} edge and in addition by XMCD at the Cr L{sub 3,2} edge using synchrotron radiation. Differences between the two methods are discussed. Despite its severe limitations for 3d transition metals, a spin sum rule evaluation is nevertheless performed for the Mn{sup III} centres in the [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} SMM to provide a simple means of comparing XMCD and spin-resolved electron spectroscopy results.

  17. Surface stabilized GMR nanorods of silver coated CrO{sub 2} synthesized via a polymer complex at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, S., E-mail: drsomnathbiswas@gmail.com [The LNM Institute of Information Technology, Jaipur-302031 (India); Singh, G.P. [Centre for Nanotechnology, Central University of Jharkhand, Ranchi-835205 (India); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India); Fecht, H.-J. [Insitut für Micro-und Nanomaterialien, Universität Ulm, Albert Einstein Allee-47, Ulm, D-89081, and Forschungszentrum Karlsruhe, Institute of Nanotechnology, Karlsruhe, D-76021 (Germany)

    2013-08-15

    Stable anisotropic nanorods of surface modified CrO{sub 2} (∼18 nm diameter) with a correlated diamagnetic layer (2–3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr{sup 4+} ions by Ag atoms on the CrO{sub 2} surface (topotactic surface layer) via an etching reaction of a CrO{sub 2}-polymer complex with Ag{sup +} ions in hot water followed by heating the dried sample at 300–400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO{sub 2} such that it no longer converts to Cr{sub 2}O{sub 3} in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO{sub 2} structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d{sub 5/2} and 3d{sub 3/2} X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (−) 7.6% at 77 K, than reported values in compacted CrO{sub 2} powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO{sub 2} nanorods. - Highlights: • Synthesis and structural studies of a novel GMR material of Ag coated CrO{sub 2}. • Tailoring useful GMR property in CrO{sub 2} nanorods of controlled shape and anisotropy. • Enhanced GMR is explained in correlation to the surface structure of CrO{sub 2} nanorods.

  18. OKMC study of the effect of grain boundaries in martensitic Fe-Cr-C alloys

    International Nuclear Information System (INIS)

    Chiapetto, M.; Becquart, C.S.; Malerba, L.

    2015-01-01

    Fe-Cr-C alloys with chromium concentrations in the range from about 2 wt % to 12 wt % form ferritic-martensitic structures by rapid cooling from the austenite state already in the presence of relatively low carbon concentrations. In this process it is possible to obtain different ratios of ferrite and martensite, as well as formation of carbides, by varying the thermal treatment. The presence of ferrite or martensite might have an influence on the nano-structural evolution under irradiation of these alloys. Here, considering a tempered martensite reference alloy with 9% Cr, we make use of an already validated object kinetic Monte Carlo (OKMC) model in order to study the possible effect of the formation of martensite laths on the material nano-structural evolution under neutron irradiation, assuming that the relevant boundaries act as sinks for radiation defects. The results show that the reduction of the grain size (including in this definition the average size of prior austenite grains, blocks and laths) does not play any relevant role until sizes of the order of about 0.5 μm are reached: for smaller grains the number of defects being absorbed by the boundaries becomes dominant. However, this threshold is lower than the experimentally observed martensite lath dimensions, thereby suggesting that what makes the difference in martensitic Fe-Cr-C alloys with respect to ferrite concerning events and mechanisms taking place during irradiation are not the lath boundaries as sinks. Differences between the nano-structural evolution in ferrite and martensite should therefore be ascribed to other factors. This document is composed of an article and the presentation slides. (authors)

  19. Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

    Science.gov (United States)

    Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

    2018-04-01

    The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

  20. Mechanism study of c.f.c Fe-Ni-Cr alloy corrosion in supercritical water

    International Nuclear Information System (INIS)

    Payet, M.

    2011-01-01

    Supercritical water can be use as a high pressure coolant in order to improve the thermodynamic efficiency of power plants. For nuclear concept, lifetime is an important safety parameter for materials. Thus materials selection criteria concern high temperature yield stress, creep resistance, resistance to irradiation embrittlement and also to both uniform corrosion and stress corrosion cracking.This study aims for supplying a new insight on uniform corrosion mechanism of Fe-Ni-Cr f.c.c. alloys in deaerated supercritical water at 600 C and 25 MPa. Corrosion tests were performed on 316L and 690 alloys as sample autoclaves taking into account the effect of surface finishes. Morphologies, compositions and crystallographic structure of the oxides were determined using FEG scanning electron microscopy, glow discharge spectroscopy and X-ray diffraction. If supercritical water is expected to have a gas-like behaviour in the test conditions, the results show a significant dissolution of the alloy species. Thus the corrosion in supercritical water can be considered similar to corrosion in under-critical water assuming the higher temperature and its effect on the solid state diffusion. For alloy 690, the protective oxide layer formed on polished surface consists of a chromia film topped with an iron and nickel mixed chromite or spinel. The double oxide layer formed on 316L steel seems less protective with an outer porous layer of magnetite and an inhomogeneous Cr-rich inner layer. For each alloy, the study of the inner protective scale growth mechanisms by marker or tracer experiments reveals that diffusion in the oxide scale is governed by an anionic process. However, surface finishes impact deeply the growth mechanisms. Comparisons between the results for the steel suggest that there is a competition between the oxidation of iron and chromium in supercritical water. Sufficient available chromium is required in order to form a thin oxide layer. Highly deformed or ultra fine

  1. Electron paramagnetic resonance study on n-type electron-irradiated 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, P; Rabia, K; Son, N T; Janzen, E [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Ohshima, T; Morishita, N; Itoh, H [Japan Atomic Energy Research Institute, Takasaki 370-1292 (Japan); Isoya, J [University of Tsukuba, Tsukuba 305-8550 (Japan)], E-mail: paca@ifm.liu.se

    2008-03-15

    Electron Paramagnetic Resonance (EPR) was used to study defects in n-type 3C-SiC films irradiated by 3-MeV electrons at room temperature with a dose of 2x10{sup 18} cm{sup -2}. After electron irradiation, two new EPR spectra with an effective spin S = 1, labeled L5 and L6, were observed. The L5 center has C{sub 3v} symmetry with g = 2.004 and a fine-structure parameter D = 436.5x10{sup -4} cm{sup -1}. The L5 spectrum was only detected under light illumination and it could not be detected after annealing at {approx}550{sup 0}C. The principal z-axis of the D tensor is parallel to the <111>-directions, indicating the location of spins along the Si-C bonds. Judging from the symmetry and the fact that the signal was detected under illumination in n-type material, the L5 center may be related to the divacancy in the neutral charge state. The L6 center has a C{sub 2v}-symmetry with an isotropic g-value of g = 2.003 and the fine structure parameters D = 547.7x10{sup -4} cm{sup -1} and E = 56.2x10{sup -4} cm{sup -1}. The L6 center disappeared after annealing at a rather low temperature ({approx}200 deg. C), which is substantially lower than the known annealing temperatures for vacancy-related defects in 3C-SiC. This highly mobile defect may be related to carbon interstitials.

  2. Magnetic properties and phase stability of half-metal-type Co2Cr1-xFexGa alloys

    International Nuclear Information System (INIS)

    Kobayashi, K.; Umetsu, R.Y.; Fujita, A.; Oikawa, K.; Kainuma, R.; Fukamichi, K.; Ishida, K.

    2005-01-01

    The magnetic properties and phase stability of half-metal-type Co 2 Cr 1-x Fe x Ga alloys were investigated by differential scanning calorimetry (DSC), in a superconducting quantum interference device (SQUID) magnetometer and in a vibrating sample magnetometer (VSM), and by transmission electron microscopy (TEM). It was found that the L2 1 -type single-phase is obtainable for the entire concentration of x and that the value of the saturation magnetic moment M s at 4.2K in the lower composition range of x is in agreement with the generalized Slater-Pauling line, while it is rather larger than the generalized Slater-Pauling line above x=0.6. The Curie temperature T c monotonically increases, whereas the transition temperature from the L2 1 - to B2-type phase T t B2/L2 1 is almost constant at 1082+/-13K with increasing x

  3. Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

    Directory of Open Access Journals (Sweden)

    Wen-Tao Yu

    2016-08-01

    Full Text Available The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix during hot processing as demonstrated by the determination of extracted carbides from the steel matrix. Meanwhile, titanium suppressed the precipitation of secondary carbides during annealing. The appropriate amount of titanium addition decreased the size and fraction of primary carbides in the as-cast ingot, and improved the mechanical properties of the annealed steel.

  4. On creep of directionally solidified eutectic Co-Cr-C-base superalloys

    International Nuclear Information System (INIS)

    Hildebrandt, U.W.

    1981-01-01

    It is shown in the present paper that the stress exponent and the activation energy of an Al-modified 73 C-alloy agree with the following mechanisms: diffusion controlled climbing of dislocation takes place and, the activation energy is in accordance with the self-diffusion energy of chromium, particularly that of Cr in Cr 7 C 3 . (orig.) [de

  5. Microstructure and Mechanical Properties of n-irradiated Fe-Cr Model Alloys

    International Nuclear Information System (INIS)

    Matijasevic, Milena; Al Mazouzi, Abderrahim

    2008-01-01

    High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems (ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160 deg. C to 300 deg. C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300 deg. C. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. (authors)

  6. Microstructural evolution in 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened stainless steel

    International Nuclear Information System (INIS)

    Ping, D.H.; Ohnuma, M.; Hirakawa, Y.; Kadoya, Y.; Hono, K.

    2005-01-01

    The microstructure of 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened (PH) stainless steel has been investigated using transmission electron microscopy, three-dimensional atom probe and small-angle X-ray scattering. A high number density (∼10 23-25 m -3 ) of ultra-fine (1-6 nm) β-NiAl precipitates are formed during aging at 450-620 deg. C, which are spherical in shape and dispersed uniformly with perfect coherency with the matrix. As the annealing temperature increases, the size and concentration of the precipitates increase concurrently while the number density decreases. The Mo and Cr segregation to the precipitate-matrix interface has been detected and is suggested to suppress precipitate coarsening. In the sample aged for 500 h at 450 deg. C, the matrix decomposes into Cr-rich (α') and Cr-poor (α) regions. The decrease in the strength at higher temperature (above 550 deg. C) is attributed to the formation of larger carbides and reverted austenite

  7. Structural, optical and magnetic properties of Cr doped SnO2 nanoparticles stabilized with polyethylene glycol

    International Nuclear Information System (INIS)

    Subramanyam, K.; Sreelekha, N.; Murali, G.; Reddy, D. Amaranatha; Vijayalakshmi, R.P.

    2014-01-01

    Pure and Cr (1, 3, 5 and 7 at%) doped SnO 2 nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO 2 nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4 2 /mnm) of SnO 2 . The peak positions with Cr concentration shifted to higher 2θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8–10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O–Sn–O entities. Further it revealed that the undoped and as well as Cr doped SnO 2 nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO 2 nanoparticles

  8. Annealing effects on structure and mechanical properties of CoCrFeNiTiAlx high-entropy alloys

    International Nuclear Information System (INIS)

    Zhang, K B; Fu, Z Y; Zhang, J Y; Wang, W M; Lee, S W; Niihara, K

    2011-01-01

    Novel CoCrFeNiTiAl x (x:molar ratio, other elements are equimolar) high-entropy alloys were prepared by vacuum arc melting and these alloys were subsequently annealed at 1000 deg. C for 2 h. The annealing effects on structure and mechanical properties were investigated. Compared with the as-cast alloys, there are many complex intermetallic phases precipitated from the solid solution matrix in the as-annealed alloys with Al content lower than Al 1.0 . Only simple BCC solid solution structure appears in the as-annealed Al 1.5 and Al 2.0 alloys. This kind of alloys exhibit high resistance to anneal softening. Most as-annealed alloys possess even higher Visker hardness than the as-cast ones. The as-annealed Al 0.5 alloys shows the highest compressive strength while the Al 0 alloy exhibits the best ductility, which is about 2.6 GPa and 13%, respectively. The CoCrFeNiTiAl x high-entropy alloys possess integrated high temperature mechanical property as well.

  9. Microstructure and mechanical properties of two Z-phase strengthened 12%Cr martensitic steels: the effects of Cu and C

    Energy Technology Data Exchange (ETDEWEB)

    Rashidi, Masoud, E-mail: masoud.rashidi@chalmers.se [Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Johansson, Lennart [Siemens Industrial Turbomachinery AB, SE-612 83 Finspong (Sweden); Andrén, Hans-Olof; Liu, Fang [Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden)

    2017-05-10

    Z-phase strengthened 12% Cr steels are designed to combine good corrosion and creep resistance for applications in fossil fuel power plants with steam temperatures up to 650 °C. Two trial Z-phase strengthened steels were investigated, Z-steel with ultra-low C content, and ZCuC-steel with relatively high C content and Cu addition. The Z-steel has better creep strength; however, the alloy has low impact toughness due to the formation of continuous Laves-phase films at grain boundaries. Atom probe tomography, transmission electron microscopy, and scanning electron microscopy were employed to study the effects of C and Cu on the microstructure of the two steels in the as-tempered condition, and after ageing for different times. The Z-steel shows a fast transformation from TaN to Z-phase. The relatively high C content in the ZCuC-steel resulted in the formation of two categories of MX: Ta(C, N) and TaN. The phase transformation from Ta(C, N) to Z-phase is slower compared to that from TaN to Z-phase. In addition, precipitation of M{sub 23}C{sub 6} and Cu particles in the ZCuC-steel led to easier nucleation of Laves-phase, and hence a much improved toughness.

  10. Synthesis and some coordination chemistry of the PSnP pincer-type stannylene Sn(NCH2PtBu2)2C6H4, attempts to prepare the PSiP analogue, and the effect of the E atom on the molecular structures of E(NCH2PtBu2)2C6H4 (E = C, Si, Ge, Sn).

    Science.gov (United States)

    Brugos, Javier; Cabeza, Javier A; García-Álvarez, Pablo; Pérez-Carreño, Enrique; Polo, Diego

    2018-03-26

    The non-donor-stabilized PSnP pincer-type stannylene Sn(NCH2PtBu2)2C6H4 (1) has been prepared by treating SnCl2 with Li2(NCH2PtBu2)2C6H4. All attempts to synthesize the analogous PSiP silylene by reduction of the (previously unknown) silanes SiCl2(NCH2PtBu2)2C6H4 (2), SiHCl(NCH2PtBu2)2C6H4 (3) and SiH(HMDS)(NCH2PtBu2)2C6H4 (4; HMDS = N(SiMe3)2) have been unsuccessful. The almost planar (excluding the tert-butyl groups) molecular structure of stannylene 1 (determined by X-ray crystallography) has been rationalized with the help of DFT calculations, which have shown that, in the series of diphosphanetetrylenes E(NCH2PtBu2)2C6H4 (E = C, Si, Ge, Sn), the most stable conformation of the compounds with E = Ge and Sn has both P atoms very close to the EN2C6H4 plane, near (interacting with) the E atom, whereas for the compounds with E = C and Si, both phosphane groups are located at one side of the EN2C6H4 plane and far away from the E atom. The size of the E atom and the strength of stabilizing donor-acceptor PE interactions (both increase on going down in group 14) are key factors in determining the molecular structures of these diphosphanetetrylenes. The syntheses of the chloridostannyl complexes [Rh{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η4-cod)] (5), [RuCl{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η6-cym)] (6) and [IrCl{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η5-C5Me5)] (7) have demonstrated the tendency of stannylene 1 to insert its Sn atom into M-Cl bonds of transition metal complexes and the preference of the resulting PSnP chloridostannyl group to act as a κ2Sn,P-chelating ligand, maintaining an uncoordinated phosphane fragment. X-ray diffraction data (of 6), 31P{1H} NMR data (of 5-7) and DFT calculations (on 6) are consistent with the existence of a weak PSn interaction involving the non-coordinated P atom of complexes 5-7, similar to that found in stannylene 1.

  11. In silico CrNF, a half-metallic ferromagnetic nitride–fluoride mimicking CrO2

    International Nuclear Information System (INIS)

    Matar, Samir F.

    2014-01-01

    Isoelectronic with CrO 2 , CrNF is proposed in silico based on rutile derived structures with DFT computations. The ground state structure defined from cohesive energies is of MgUO 4 -type, characterized by short covalent Cr–N and long ionic Cr–F distances. Like CrO 2 it is a half-metallic ferromagnet with M=2 μ B /FU integer magnetization with reduced band gap at minority spins. Major difference of magnetic response to pressure characterizes CrNF as a soft ferromagnet versus hard magnetic CrO 2 . The chemical bonding properties point to prevailing covalent Cr–N versus ionic Cr–F bonding. Different synthesis routes are examined. - Highlights: • DFT identification of CrNF is based on isoelectronicity and rutile derivatives. • Similarly to CrO 2 , CrNF is a half-metallic ferromagnet with reduced band gap. • Strong pressure dependence of magnetization of CrNF oppositely to CrO 2 . • Covalent Cr–N bonding prevails in spite of the presence of ionic Cr–F. • Cohesive energies favor the synthesis for which protocols are proposed

  12. Study of phase transformations of Fe-Cr-C system using the technique of differential scanning calorimetry

    International Nuclear Information System (INIS)

    Facal, L.S.; Noreña, H. C.; Bruzzoni, P.

    2013-01-01

    The family of 9% Cr-1% Mo steels has been considered by The Generation IV International Forum as candidate materials for the construction of these prospective advanced nuclear reactors. A simple system related with these steels is the Fe-Cr-C system. In this work, a laboratory made Fe-10% Cr-0,1% C alloy has been studied. Particularly, the effect of the cooling rate on the transformations that take place when the alloy is cooled from the austenitic field was analyzed. To perform this analysis two techniques have been used: The differential scanning calorimetry (DSC) and the scanning electron microscopy (SEM). Different cooling rates of 4, 10, 50 and 90 °C/min were tested in the DSC and the resulting microstructures were observed by SEM. At the rates of 50 and 90 °C/min the cooling treatment produced a martensitic structure. Contrarily, cooling at a rate of 4 °C/min produced a microstructure consisting mainly of ferrite-pearlite with a low fraction of martensite. In the heating step which followed the cooling step, the magnetic transformation is well resolved as a broad peak which presents a maximum at 753 ± 1 °C for all the cooling rates. (author) [es

  13. Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C6H6, C6D6, and C6F6+CO2

    International Nuclear Information System (INIS)

    Sedlacek, A.J.; Weston, R.E. Jr.; Flynn, G.W.

    1991-01-01

    The vibrational relaxation of highly excited ground state benzene, benzene d 6 , and hexafluorobenzene by CO 2 has been investigated with high resolution diode laser spectroscopy. The vibrationally hot polyatomics are formed by single photon 248 nm excitation to the S 1 state followed by rapid radiationless transitions. It has been found that in all cases less than 1% of the energy initially present in the polyatomics is deposited into the high frequency mode of CO 2 (ν 3 ). An investigation of the CO 2 (00 0 1) nascent rotational distribution under single collision conditions reveals that very little rotational excitation accompanies vibrational energy transfer to the ν 3 mode. The CO 2 (ν 3 ) rotational states can be described by temperatures, T rot , as follows: C 6 H 6 , T rot =360±30 K; C 6 D 6 , T rot =350±35 K and C 6 F 6 , T rot =340±23 K. An estimate of left-angle ΔE right-angle ν3 , the mean energy transferred to the CO 2 ν 3 mode per collision, suggests that as the availability of low frequency modes in the excited molecule increases, less energy is deposited into the high frequency mode of CO 2 . Finally, evidence is presented suggesting that even at moderate laser fluences, the two-photon ionization of benzene can lead to substantial CO 2 ν 3 excitation via electron+CO 2 inelastic collisions

  14. Effects of alloying and temperature on the high-temperature oxidation of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H. [Oak Ridge National Lab., TN (United States); Carson, L.J. [Lincoln Univ., PA (United States)

    1993-06-01

    Effects of alloying additions and temperature on isothermal and cyclic oxidation resistance of Cr-Cr{sub 2}Nb alloys were examined for air exposures. An isothermal exposure temperature of 1100C led to rapid reaction of binary Cr-12 at.% Nb as manifested a high oxidation rate and nonprotective behavior. Generally parabolic kinetics, complicated by some isothermal scale cracking, were observed at 900--1000C. Scale damage was exacerbated by thermal cycling. The addition of 8 at.% Al to Cr-12 at.% Nb did not effect cyclic oxidation resistance, but there was some evidence that scale adherence on Cr-6 at.% Nb-8 at.% Al was better than that for binary Cr-6 at.% Nb. Alloying additions of Al (up to 18 at.%) or Re (2 at.%) did not improve the isothermal oxidation resistance of Cr-12 at.% Nb. However, the tendency for scale damage during both isothermal and thermal cycling exposures suggests that alloying additions that specifically improve scale plasticity or modify growth stresses could be effective for Cr-Nb alloys. 10 refs, 9 figs, 1 tab.

  15. Structural, electrical, and dielectric properties of Cr doped ZnO thin films: Role of Cr concentration

    Energy Technology Data Exchange (ETDEWEB)

    Gürbüz, Osman, E-mail: osgurbuz@yildiz.edu.tr; Okutan, Mustafa

    2016-11-30

    Highlights: • Magnetic material of Cr and semiconductor material of ZnO were grown by the magnetron sputtering co-sputter technique. • Perfect single crystalline structures were grown. • DC and AC conductivity with dielectric properties as a function of frequency (f = 5Hz–13 MHz) at room temperature were measured and compared. • Cr doped ZnO can be used in microwave, sensor and optoelectronic devices as the electrical conductivity increases while dielectric constant decreases with the Cr content. - Abstract: An undoped zinc oxide (ZnO) and different concentrations of chromium (Cr) doped ZnO Cr{sub x}ZnO{sub 1−x} (x = 3.74, 5.67, 8.10, 11.88, and 15.96) thin films were prepared using a magnetron sputtering technique at room temperature. These films were characterized by X-ray diffraction (XRD), High resolution scanning electron microscope (HR-SEM), and Energy dispersive X-ray spectrometry (EDS). XRD patterns of all the films showed that the films possess crystalline structure with preferred orientation along the (100) crystal plane. The average crystallite size obtained was found to be between 95 and 83 nm which was beneficial in high intensity recording peak. Both crystal quality and crystallite sizes decrease with increasing Cr concentration. The crystal and grain sizes of the all film were investigated using SEM analysis. The surface morphology that is grain size changes with increase Cr concentration and small grains coalesce together to form larger grains for the Cr{sub 11.88}ZnO and Cr{sub 15.96}ZnO samples. Impedance spectroscopy studies were carried out in the frequencies ranging from 5 Hz to 13 MHz at room temperature. The undoped ZnO film had the highest dielectric value, while dielectric values of other films decreased as doping concentrations increased. Besides, the dielectric constants decreased whereas the loss tangents increased with increasing Cr content. This was considered to be related to the reduction of grain size as Cr content in Zn

  16. Heredity of medium-range order structure from melts to the microstructure of Ni-Cr-W superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhongtang; Hu, Rui; Wang, Jun; Li, Jinshan [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an (China)

    2015-07-15

    The structure factor S(Q), intensities and pair distribution function g(r) of liquid Ni-Cr-W superalloy at different temperatures have been measured by a high-temperature X-ray diffractometer. Coordination N{sub min}, correlation radius r{sub c}, the nearest atomic distance r{sub 1}, solidification microstructure and compression performance have been studied. The results show that a pre-peak exists on the structure factor curve at the liquidus temperature, and a fine structure of equiaxed, globular and non-dendritic primary grains can be achieved by casting the alloy at liquidus temperature. Liquid structure feature of Ni-Cr-W superalloy is found to depend on temperature. During the solidification, some structural information carried by the medium-range order (MRO) structure is inherited from the melt to the microstructure, which is beneficial for grain refinement. The maximum yield strength measured from typical microstructure of the equiaxed and non-dendritic grains at 1400 C is 543 MPa. The results show that refinement and non-dendritic grain is beneficial to the improvement of the yield strength. (orig.)

  17. Study of the structural, electronic and magnetic properties of ScFeCrT (T=Si, Ge) Heusler alloys by first principles approach

    Energy Technology Data Exchange (ETDEWEB)

    Rasool, Muhammad Nasir [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Hussain, Altaf, E-mail: altafiub@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Javed, Athar, E-mail: athar.physics@pu.edu.pk [Department of Physics, University of the Punjab, Lahore 54590 (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan)

    2017-03-15

    Spin polarized structural, electronic, magnetic and bonding properties of ScFeCrT (T=Si, Ge) Heusler alloys are studied by employing density functional theory. The total energy calculation (for a static lattice) shows that both alloys are structurally stable in ferromagnetic phase with compressibility C{sub ScFeCrSi}>C{sub ScFeCrGe}. The electronic and band structure analysis show that the ScFeCrT alloys exhibit half-metallic ferromagnetic (HMF) behaviour for spin ↑ channel while semiconducting behaviour in spin ↓ channel. Both alloys exhibit total magnetic moment, M{sub Total}=3.0 µ{sub B}/cell obeying the Slater Pauling rule, M{sub SPR}=(N{sub v} –18)μ{sub B}. For ScFeCrSi and ScFeCrGe alloys, the charge density and interatomic bonding character show highly covalent and polar covalent character, respectively. For both alloys, 100% spin polarization (for spin ↑ state) is expected which is an indication of their suitability for applications in spintronic devices. - Highlights: • Heusler alloys ScFeCrT (T= Si, Ge) are studied by first principles approach. • Structural, electronic, magnetic and bonding properties are reported. • Both alloys show half-metallicity and ferromagnetic behaviour. • Combination of properties shows the suitability of alloys in spintronic devices.

  18. Cesium immobilization in (Ba,Cr)-hollandites: Effects on structure

    Science.gov (United States)

    Tumurugoti, Priyatham; Sundaram, S. K.; Misture, Scott T.

    2018-02-01

    Hollandites with compositions Ba1.15-xCs2xCr2.3Ti5.7O16 (0 ≤ x ≤ 1.15) intended for the immobilization of cesium (Cs) from nuclear waste have been prepared, characterized, and analyzed for Cs retention properties. Sol-gel synthesized powders were used for structural characterization using a combination of X-ray, neutron, and electron diffraction techniques. Phase-pure hollandites adopting tetragonal (I4/m) or monoclinic symmetry (I2/m) were observed to form in the compositional range 0 ≤ x ≤ 0.4. Structural models for the compositions, x = 0, 0.15, and 0.25 were developed from Rietveld analysis of powder diffraction data. Refined anisotropic displacement parameters (βij) for the Ba and Cs ions in the hollandite tunnels indicate local disorder of Ba/Cs along the tunnel direction. In addition, weak superlattice reflections were observed in X-ray and electron diffraction patterns that were due to the compositional modulation i.e., ordering of ions and vacancies along tunnel direction. Our overall observations suggest the phase-pure hollandites studied assumed supercell structures with ordered tunnel cations, which in turn have positional disorder in individual supercells.

  19. Determination of the Cu(110)-c(6X2)-O structure by x-ray diffraction

    DEFF Research Database (Denmark)

    Feidenhans'l, R.; Grey, F.; Johnson, R.L.

    1991-01-01

    a reduced mean-square residual of chi-2 = 1.9, and includes most of the features known from the literature, with 5/6 of a monolayer of Cu atoms considerably displaced away from ideal lattice sites, two different oxygen sites, and an oxygen coverage of 2/3 of a monolayer. The structure contains Cu-O chains...

  20. Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals

    Energy Technology Data Exchange (ETDEWEB)

    Nevasmaa, P.; Salonen, J.; Holmstroem, S. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2007-06-15

    In comparison with conventional creep resisting grade T/P22, the modified 2%Cr steels T/P23 and T/P24 show nearly twice the creep strength at typical service temperatures of about 520-570 deg C. The possibility of welding thin-wall boiler tubes without preheating or PWHT has promoted the use of T23 and T24 in practical boiler service. For thick-wall applications and multipass welds, welding consumables still require further development to improve creep strength and ductility. Susceptibility to reheat cracking and hydrogen cracking increase with the wall-thickness and structural rigidity of the component. Consequently, thick-wall sections generally require the use of PWHT and sometimes preheating as well. This paper is concerned with weldability of P23 pipe steel, with particular emphasis on reheat cracking sensitivity of simulated HAZ microstructures and thick-section multipass welds made using closely matching and mis-matching filler metals. The results demonstrate that the weld metal is far more critical than the parent steel HAZ, both in terms of reheat cracking sensitivity and ductility and toughness. In the as-welded condition, the weld metal exhibited excessive hardness of {approx}380 HV and only diminutive Charpy toughness at room temperature. Adoption of the PWHT (760 deg C/2h) enhanced the weldment toughness; however, it also inevitably raises risk to reheat cracking in the weld metal that showed values of reduction of area (RA) no more than 2-3% in the BWI cracking test. The results imply that thick-section multipass welds made using filler metal with the chemical composition closer to P24 grade material are much less susceptible to reheat cracking than 'matching' P23 grade welds. (orig.)

  1. Assembly and Regulation of the Membrane Attack Complex Based on Structures of C5b6 and sC5b9

    Directory of Open Access Journals (Sweden)

    Michael A. Hadders

    2012-03-01

    Full Text Available Activation of the complement system results in formation of membrane attack complexes (MACs, pores that disrupt lipid bilayers and lyse bacteria and other pathogens. Here, we present the crystal structure of the first assembly intermediate, C5b6, together with a cryo-electron microscopy reconstruction of a soluble, regulated form of the pore, sC5b9. Cleavage of C5 to C5b results in marked conformational changes, distinct from those observed in the homologous C3-to-C3b transition. C6 captures this conformation, which is preserved in the larger sC5b9 assembly. Together with antibody labeling, these structures reveal that complement components associate through sideways alignment of the central MAC-perforin (MACPF domains, resulting in a C5b6-C7-C8β-C8α-C9 arc. Soluble regulatory proteins below the arc indicate a potential dual mechanism in protection from pore formation. These results provide a structural framework for understanding MAC pore formation and regulation, processes important for fighting infections and preventing complement-mediated tissue damage.

  2. Mehanička svojstva i mikrostruktura vakuum plazma naprskane Cr3C2 - 25(Ni20Cr prevlake / Mechanical properties and microstructure of vacuum plasma sprayed Cr3C2 – 25(Ni20Cr coatings / Механические свойства и микроструктура покрытия Cr3C2 - 25(Ni20Cr нанесенного методом вакуумного плазменного напыления

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2015-04-01

    of the coating was tested by tension. It was found that the bond strength between the substrate and the coating has a value of 89 MPa. The microstructure of the coating was tested by the light microscopy technique. The structure of the coating consists of an NiCr alloy base with a dominant primary Cr3C2 carbide phase. In addition to the Cr3C2 phase, the Cr7C3 phase is also present. The coating etching was done with the reagent 1HNO3 : 4HCl : 4H2O that primarily dissolves nickel to enable the distribution of the carbide phase to be clearly seen in the coating. Etching the coating with this reagent revealed the presence of the largely undegraded primary Cr3C2 carbide phase which provides high hardness values to the coating. / В данной работе анализируется метод вакуумного плазменного напыления покрытия Cr3C2 - 25(Ni20Cr с использованием промышленного порошкового состава Sulzer Metco Woka 7205 при применении плазматрона F4 на расстоянии 340мм от основания. Основной целью работы является проверка утверждения, что при пониженном давлении инертного газа исключается распад первичного карбида Cr3C2 до карбида Cr23C6, который значительно снижает микротвердость и механические свойства. Покрытие толщиной 100 – 120 µm наносилось на стальное основание. Испытания покрытия на микротведость проводились по методу HV0.3. Значения показателей микротвердости находятся в промежутке 1248 - 1342 HV0.3. Испытание адгезии покрытия к основанию

  3. Doping of 6H-SiC pn structures by proton irradiation

    International Nuclear Information System (INIS)

    Strel'chuk, Anatoly M.; Lebedev, Alexandre A.; Kozlovski, Vitali V.; Savkina, Natali S.; Davydov, Denis V.; Solov'ev, Viktor V.; Rastegaeva, Marina G.

    1999-01-01

    The influence of proton irradiation on current-voltage characteristics, N d - N a values and parameters of deep centres in 6H-SiC pn structures grown by sublimation epitaxy has been studied. The irradiation was carried out with 8 MeV protons in the range of doses from 10 14 to 10 16 cm -2 . Irradiation with a dose of 3.6x10 14 cm -2 leaves the voltage drop at high forward currents (10 A/cm 2 ) practically unchanged. For higher irradiation dose of 1.8x10 15 cm -2 , the forward voltage drop and the degree of compensation in the samples increased ; partial annealing of the radiation defects and partial recovery of the electrical parameters occurred after annealing at T∼400-800 K. Irradiation with a dose of 5.4x10 15 cm -2 resulted in very high resistance in forward biased pn structures which remained high even after heating to 500 deg. C. It is suggested that proton irradiation causes decreasing of the lifetime and formation of an i- or an additional p-layer

  4. /sup 51/Cr-EDTA//sup 14/C-mannitol intestinal permeability test. Clinical use in screening for coeliac disease

    Energy Technology Data Exchange (ETDEWEB)

    Fotherby, K.J.; Wraight, E.P.; Neale, G.

    1988-01-01

    An intestinal permeability test with a combination of /sup 51/Cr-EDTA and /sup 14/C-mannitol was performed under routine conditions on 176 occasions in 161 adult patients. Of these patients, 116 were under investigation for possible coeliac disease, 33 were known to have coeliac disease, and 12 had inflammatory bowel disease. Small-bowel biopsies were performed in 61 patients. Expressing the results as the ratio of the 6-h urinary recoveries of the two probes was as sensitive as 95%, but more specific for histological mucosal abnormality (62% versus 46%) than measuring the urinary recovery of /sup 51/Cr-EDTA alone. All but two of the patients with active inflammatory bowel disease, whether Crohn's disease or ulcerative colitis, had an abnormal ratio. The /sup 51/Cr-EDTA//sup 14/C-mannitol intestinal permeablity test with a 6-h urine collection is a rapid and simple test of small-intestinal function suitable for routine use. 19 refs.

  5. Microstructure and morphology of powder particles TiC-NiCr, synthesized in plasma jet, at high-energy actions on components of initial composition Ti-C-NiCr

    Science.gov (United States)

    Solonenko, Oleg P.; Smirnov, Andrey V.; Chesnokov, Anton E.

    2017-10-01

    The results of experiments on in-situ synthesis of the microspherical, in particular hollow, cermet powder TiC- 30vol.%NiCr at processing of the Ti-C-NiCr agglomerates in argon-helium plasma jet flowing out into controlled atmosphere are presented. Preparation of the agglomerates consisted of the following stages: (i) high-energy treatment of the initial powders Ti and NiCr in planetary mill with their subsequent uniform mixing with glass black powder, (ii) preparation of dough from mechanically mixed powders and binder, and their granulation using the extrusion method, (iii) drying and classification of granules by the sizes.

  6. Modification of chemical, optical and structural properties of Bayfol CR-6-2 using gamma and neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shehata, Mohamed M.; Radwan, Samh I.; Hassan, Amin [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Centre; Waly, Sayed A. [Atomic Energy Authority, Cairo (Egypt). Second Research Reactor; Badawy, Zaynab M. [Atomic Energy Authority, Cairo (Egypt). Experimental Nuclear Physics Dept.

    2016-08-01

    The effects of gamma and neutron irradiations on the chemical, optical and structural properties of Bayfol CR-6-2 were investigated. The samples were irradiated by γ-rays from a {sup 60}Co source at various doses ranging between 16 and 900 kGy at room temperature in atmospheric air. For neutrons, an Am-Be neutron facility was used for the sample irradiation in thermal mode which had an activity of 185 GBq. Samples were irradiated with different doses of neutrons ranging from 15.7 to 564.2 mGy. The changes induced were analyzed using UV-Vis and Fourier transform infrared (FTIR) spectrometry. The results demonstrated an occurrence of oxidative degradation, resulting in the formation of carbonyl groups at 1700 cm{sup -1}. Simultaneous thermo-gravimetric investigation (TGA) has been performed on the samples of 0.3 mm thickness. The results obtained indicate that cross-linking predominates at small neutron doses and main chain scission happens at higher doses.

  7. Oxidation study of Cr-Ru hard coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw; Kuo, Yu-Chu; Chen, Sin-Min

    2012-01-01

    Cr-Ru alloy coatings with Cr content ranging from 47 to 83 at.% were deposited at 400 Degree-Sign C by direct current magnetron co-sputtering with a Ti interlayer on silicon substrates. With a total input power of 300 W, the Cr content in the Cr-Ru coatings increased linearly with the increasing input power of Cr. The intermetallic compound phase Cr{sub 2}Ru with columnar structure was identified for the as-deposited Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings, resulting in an increase of hardness up to 15-16 GPa. To evaluate the performance of Cr-Ru coatings as a protective coating on glass molding dies, the annealing treatment was conducted at 600 Degree-Sign C in a 50 ppm O{sub 2}-N{sub 2} atmosphere. The outward diffusion and preferential oxidization of Cr in the Cr-Ru coatings resulted in the variations of the crystalline structure, chemical composition distribution, and surface hardness after annealing. X-ray diffraction and transmission electron microscopy (TEM) proved that an oxide scale consisting of Cr{sub 2}O{sub 3} formed on the free surface. Scanning electron microscopy and TEM observed the surface morphology and structural variation. The chemical composition depth profiles were analyzed by Auger electron microscopy, verifying the presence of a Cr-depleted zone beneath the oxide scale. The hardness of Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings decreased to 11-12 GPa after annealing, accompanied by the replacement of the Cr{sub 2}Ru phase by the Ru phase. - Highlights: Black-Right-Pointing-Pointer We prepared crystalline Cr-Ru alloy coatings by direct current magnetron sputtering. Black-Right-Pointing-Pointer Cr-Ru coatings were annealed at 600 Degree-Sign C for 2 h in a 50 ppm O{sub 2}-N{sub 2} atmosphere. Black-Right-Pointing-Pointer Cr diffused outwardly and oxidized to form a stable and protective oxide scale. Black-Right-Pointing-Pointer The original columnar grains recrystallized to polycrystalline grains.

  8. The characteristics of precipitates in 18% Cr/30% Ni cast steel with additions of Nb and Ti

    International Nuclear Information System (INIS)

    Piekarski, B.

    1995-01-01

    The microstructure of austenitic cast steel with approx. 0.3%C, 4.37%Si, 0.69%Mn, 17.8%Cr, 29.3%Ni, 1.47%Nb and 1.07%Ti have been examined after ageing at 900 C for 300 h. There was found five precipitates: M 23 C 6 , MnS, Ni 3 Fe, (Ti,Nb)C and an intermetallic Ni-Nb-S phase. Ni, Nb, Si-rich precipitate could have been formed in as cast condition. (author)

  9. Monoclonal antibody OKB7, which identifies the 14OKd complement receptor type 2 (CR/sub 2/), also identifies a 72Kd secreted fragment of CR/sub 2/ that contains the C3d-binding site

    Energy Technology Data Exchange (ETDEWEB)

    Myones, B.L.; Ross, G.D.

    1986-03-05

    CR/sub 2/ is a 140-145Kd glycoprotein expressed on B lymphocytes which binds both C3d and Epstein-Barr virus (EBV). OKB7, an IgG/sub 2a/ monoclonal antibody to CR/sub 2/, blocks C3d and EBV binding, while HB-5, another monoclonal IgG/sub 2a/ anti-CR/sub 2/, does not. A 72Kd C3d-binding glycoprotein (gp72), isolated from Raji cell media, was previously thought to be CR/sub 2/ because a polyclonal rabbit anti-gp72 inhibited EC3d rosettes. ELISA assay demonstrated that OKB7, but not HB-5, bound to purified gp72 fixed to microtiter wells. Insoluble and soluble gp72 blocked Raji cell uptake of /sup 125/I-labeled OKB7, but not labeled anti-B2 or HB-5. Rabbit anti-gp72 immunoprecipitated bands at 140Kd and 72Kd from /sup 125/I-labelled and solubilized B cell membranes. Culture media from Raji cells grown in the presence /sup 3/H-labeled amino acids was sequentially immunoprecipitated by irrelevant antibody, OKB7, and HB-5. A single 72Kd radiolabeled band was demonstrated only with OKB7, and this was identical to that produced by the immunoprecipitation of /sup 125/I-labeled gp72 with rabbit anti-gp72. Thus, OKB7, which identifies the 140Kd CR/sub 2/ molecule, also identifies a 72Kd shed fragment of CR/sub 2/ isolated from Raji cell media, which contains the C3d-binding site.

  10. Structural and magnetic studies of Cr doped nickel ferrite thin films

    International Nuclear Information System (INIS)

    Panwar, Kalpana; Heda, N. L.; Tiwari, Shailja; Bapna, Komal; Ahuja, B. L.; Choudhary, R. J.; Phase, D. M.

    2016-01-01

    We have studied the structural and magnetic properties of Cr doped nickel ferrite thin films deposited on Si (100) and Si (111) using pulsed laser deposition technique. The films were deposited under vacuum and substrate temperature was kept at 700°C. X-ray diffraction analysis revealed that films on both substrates have single phase cubic spinel structure. However, the film grown on Si (111) shows better crystalline behavior. Fourier transform infrared spectroscopy suggests that films on both substrates have mixed spinel structure. These films show magnetic hysteresis behavior and magnetization value of film on Si (100) is larger than that on Si (111). It turns out that structural and magnetic properties of these two films are correlated.

  11. Tuning the band gap of PbCrO{sub 4} through high-pressure: Evidence of wide-to-narrow semiconductor transitions

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Física Aplicada-ICMUV, Universitat de València, MALTA ConsoliderTeam, C/Dr. Moliner 50, 46100 Burjassot (Spain); Bandiello, E.; Segura, A. [Departamento de Física Aplicada-ICMUV, Universitat de València, MALTA ConsoliderTeam, C/Dr. Moliner 50, 46100 Burjassot (Spain); Hamlin, J.J.; Maple, M.B. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Rodriguez-Hernandez, P.; Muñoz, A. [Departamento de Física Fundamental II, Instituto de Materiales y Nanotecnología, Universidad de La Laguna, MALTA ConsoliderTeam, La Laguna, 38205 Tenerife (Spain)

    2014-02-25

    Highlights: • Electronic and optical properties of PbCrO{sub 4} are studied under compression. • Band-gap collapses are observed and correlated with structural phase transitions. • PbCrO{sub 4} band-gap is reduced from 2.3 to 0.8 eV in a 20 GPa range. • PbCrO{sub 4} is an n-type semiconductor with donor levels associated to Frenkel defects. • A deep-to-shallow donor transformation at HP induces a large resistivity decrease. -- Abstract: The electronic transport properties and optical properties of lead(II) chromate (PbCrO{sub 4}) have been studied at high pressure by means of resistivity, Hall-effect, and optical-absorption measurements. Band-structure first-principle calculations have been also performed. We found that the low-pressure phase is a direct band-gap semiconductor (Eg = 2.3 eV) that shows a high resistivity. At 3.5 GPa, associated to a structural phase transition, a band-gap collapse takes place, becoming Eg = 1.8 eV. At the same pressure the resistivity suddenly decreases due to an increase of the carrier concentration. In the HP phase, PbCrO{sub 4} behaves as an n-type semiconductor, with a donor level probably associated to the formation of oxygen vacancies. At 15 GPa a second phase transition occurs to a phase with Eg = 1.2 eV. In this phase, the resistivity increases as pressure does probably due to the self-compensation of donor levels and the augmentation of the scattering of electrons with ionized impurities. In the three phases the band gap red shifts under compression. At 20 GPa, Eg reaches a value of 0.8 eV, behaving PbCrO{sub 4} as a narrow-gap semiconductor.

  12. Unique structure of iC3b resolved at a resolution of 24 Å by 3D-electron microscopy.

    Science.gov (United States)

    Alcorlo, Martin; Martínez-Barricarte, Ruben; Fernández, Francisco J; Rodríguez-Gallego, César; Round, Adam; Vega, M Cristina; Harris, Claire L; de Cordoba, Santiago Rodríguez; Llorca, Oscar

    2011-08-09

    Activation of C3, deposition of C3b on the target surface, and subsequent amplification by formation of a C3-cleaving enzyme (C3-convertase; C3bBb) triggers the effector functions of complement that result in inflammation and cell lysis. Concurrently, surface-bound C3b is proteolyzed to iC3b by factor I and appropriate cofactors. iC3b then interacts with the complement receptors (CR) of the Ig superfamily, CR2 (CD21), CR3 (CD11b/CD18), and CR4 (CD11c/CD18) on leukocytes, down-modulating inflammation, enhancing B cell-mediated immunity, and targeting pathogens for clearance by phagocytosis. Using EM and small-angle X-ray scattering, we now present a medium-resolution structure of iC3b (24 Å). iC3b displays a unique conformation with structural features distinct from any other C3 fragment. The macroglobulin ring in iC3b is similar to that in C3b, whereas the TED (thioester-containing domain) domain and the remnants of the CUB (complement protein subcomponents C1r/C1s, urchin embryonic growth factor and bone morphogenetic protein 1) domain have moved to locations more similar to where they were in native C3. A consequence of this large conformational change is the disruption of the factor B binding site, which renders iC3b unable to assemble a C3-convertase. This structural model also justifies the decreased interaction between iC3b and complement regulators and the recognition of iC3b by the CR of the Ig superfamily, CR2, CR3, and CR4. These data further illustrate the extraordinary conformational versatility of C3 to accommodate a great diversity of functional activities.

  13. Phase transitions of doped carbon in CrCN coatings with modified mechanical and tribological properties via filtered cathodic vacuum arc deposition

    International Nuclear Information System (INIS)

    Guan, J.J.; Wang, H.Q.; Qin, L.Z.; Liao, B.; Liang, H.; Li, B.

    2017-01-01

    The CrCN coatings were fabricated onto Si (1 1 1) wafers and SUS304 stainless steel plates using filtered cathodic vacuum arc deposition (FCVAD) technique under different flow ratios of N_2/C_2H_2 gas mixture. The morphology, crystalline structure and chemical composition of the coatings were characterized. It was found that the grain size reduce with increasing carbon content, which makes the CrCN coatings refined and smooth. The quasi-one-dimensional carbolite phase was also found in CrN host lattice with C_2H_2 content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CN_x phases as C_2H_2 content exceeds 20%. Moreover, we examined the mechanical and tribological properties of the CrCN coatings, and the experimental results confirmed that the friction coefficient of the coatings descend to the lowest value as 0.39 with 30% C_2H_2 content, due to the graphite (sp"2 C−C) phase embed in CrN host lattice; while the chromium carbon (Cr_3C_2) and diamond (sp"3 C−C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C_2H_2 content.

  14. Phase transitions of doped carbon in CrCN coatings with modified mechanical and tribological properties via filtered cathodic vacuum arc deposition

    Science.gov (United States)

    Guan, J. J.; Wang, H. Q.; Qin, L. Z.; Liao, B.; Liang, H.; Li, B.

    2017-04-01

    The CrCN coatings were fabricated onto Si (1 1 1) wafers and SUS304 stainless steel plates using filtered cathodic vacuum arc deposition (FCVAD) technique under different flow ratios of N2/C2H2 gas mixture. The morphology, crystalline structure and chemical composition of the coatings were characterized. It was found that the grain size reduce with increasing carbon content, which makes the CrCN coatings refined and smooth. The quasi-one-dimensional carbolite phase was also found in CrN host lattice with C2H2 content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CNx phases as C2H2 content exceeds 20%. Moreover, we examined the mechanical and tribological properties of the CrCN coatings, and the experimental results confirmed that the friction coefficient of the coatings descend to the lowest value as 0.39 with 30% C2H2 content, due to the graphite (sp2 Csbnd C) phase embed in CrN host lattice; while the chromium carbon (Cr3C2) and diamond (sp3 Csbnd C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C2H2 content.

  15. Ab initio study of cubic complex Bi2CrCuO6 perovskite

    International Nuclear Information System (INIS)

    Fajardo, F.; Cardona, R.; Landinez Tellez, D.A.; Arbey Rodriguez M, J.; Roa-Rojas, J.

    2008-01-01

    We report a detailed calculation of the structural and electronic properties for the cubic complex Bi 2 CrCuO 6 perovskite material by density functional theory. The exchange-correlation potential was included through the generalized gradient approximation. From the adjusting of Murnaghan state equation to the energy as a function of volume data, we obtain an ideal lattice parameter of 7.763 A. The density of states study was carried out considering the two spin polarizations. Results reveal that this material behaves as a conductor to the spin-down polarization and evidence a semiconductor tendency to the spin-up configuration. This tendency to the half-metallicity character is corroborated by the integer number of magnetic moment (3.0 μ B ), which is attributed to the Cr-spin-up orbital contribution

  16. Half-metallic behavior and electronic structure of Sr2CrMoO6 magnetic system

    International Nuclear Information System (INIS)

    Bonilla, C.M.; Landinez Tellez, D.A.; Arbey Rodriguez, J.; Vera Lopez, E.; Roa-Rojas, J.

    2007-01-01

    Complex perovskite materials with the A 2 BB'O 6 formula have been recently studied because of their peculiar magnetic and electronic properties. The origin of magnetism in the double perovskite Sr 2 FeMoO 6 brought these properties again into discussion. Recently, a new interaction mechanism was proposed for cases in which the hybridization of 3d and 2p levels of Mo with the 3d Fe levels is responsible for the half-metallic behavior in the Sr 2 FeMoO 6 material. We report on LAPW ab initio calculations within the generalized gradient approximation (GGA) to density functional theory (DFT) for another double perovskite, namely, Sr 2 CrMoO 6 . Our results show that this is also a half-metallic system. We correlate our results with an extension of the recent model proposed by Sarma to explain the conduction mechanism in this compound

  17. Microstructure and mechanical properties of nanostructure multilayer CrN/Cr coatings on titanium alloy

    International Nuclear Information System (INIS)

    Wiecinski, Piotr; Smolik, Jerzy; Garbacz, Halina; Kurzydlowski, Krzysztof J.

    2011-01-01

    Five different nanostructured, multilayer coatings (CrN/Cr)x8 with different thickness ratio of Cr and CrN layers were deposited by PAPVD (Plasma Assisted Physical Vapour Deposition) vacuum arc method on Ti6Al4V titanium alloy. The microstructure, chemical and phase composition of the CrN and Cr sub-layers were characterized by SEM with EDX and Cs-corrected dedicated STEM on cross-sections prepared by focus ion beam. Besides, hardness and Young's modulus of the (Cr/CrN)x8 coatings has been measured. The adhesion has been tested by scratch test method. The obtained (CrN/Cr) multilayer coatings, 5-6 μm in thickness, have homogeneous and nanocrystalline structure, free of pores and cracks. The microstructures of Cr and CrN layers consist of columnar grains below 100 nm in diameter. The hardness and Young's modulus of these coatings depend linearly on thickness ratio of Cr and CrN layers. The decrease of the thickness ratio Cr/CrN 0.81 to 0.15 results in the increase of hardness from 1275 HV to 1710 HV and Young's modulus from 260 GPa to 271 GPa.

  18. High Production of 2,3-Butanediol (2,3-BD by Raoultella ornithinolytica B6 via Optimizing Fermentation Conditions and Overexpressing 2,3-BD Synthesis Genes.

    Directory of Open Access Journals (Sweden)

    Taeyeon Kim

    Full Text Available Biological production of 2,3-butandiol (2,3-BD has received great attention as an alternative to the petroleum-based 2,3-BD production. In this study, a high production of 2,3-BD in fed-batch fermentation was investigated with a newly isolated bacterium designated as Raoultella ornithinolytica B6. The isolate produced 2,3-BD as the main product using hexoses (glucose, galactose, and fructose, pentose (xylose and disaccharide (sucrose. The effects of temperature, pH-control schemes, and agitation speeds on 2,3-BD production were explored to optimize the fermentation conditions. Notably, cell growth and 2,3-BD production by R. ornithinolytica B6 were higher at 25°C than at 30°C. When three pH control schemes (no pH control, pH control at 7, and pH control at 5.5 after the pH was decreased to 5.5 during fermentation were tested, the best 2,3-BD titer and productivity along with reduced by-product formation were achieved with pH control at 5.5. Among different agitation speeds (300, 400, and 500 rpm, the optimum agitation speed was 400 rpm with 2,3-BD titer of 68.27 g/L, but acetic acid was accumulated up to 23.32 g/L. Further enhancement of the 2,3-BD titer (112.19 g/L, yield (0.38 g/g, and productivity (1.35 g/L/h as well as a significant reduction of acetic acid accumulation (9.71 g/L was achieved by the overexpression of homologous budABC genes, the 2,3-BD-synthesis genes involved in the conversion of pyruvate to 2,3-BD. This is the first report presenting a high 2,3-BD production by R.ornithinolytica which has attracted little attention with respect to 2,3-BD production, extending the microbial spectrum of 2,3-BD producers.

  19. Cucurbitane-type triterpenoids from the fruit pulp of Momordica charantia.

    Science.gov (United States)

    Liao, Yun-Wen; Chen, Chiy-Rong; Kuo, Yueh-Hsiung; Hsu, Jue-Liang; Shih, Wen-Ling; Cheng, Hsueh-Ling; Huang, Tzou-Chi; Chang, Chi-I

    2012-12-01

    Three new cucurbitane-type triterpenoids, 5beta,19-epoxy-23(R)-methoxycucurbita-6,24-dien-3beta-ol (1), 5beta,19-epoxy-23(S)-methoxycucurbita-6,24-dien-3beta-ol (2), and 3beta-hydroxy-23(R)-methoxycucurbita-6,24-dien-5beta,19-olide (3), were isolated from the fruit pulp of Momordica charantia. Their structures were established on the basis of extensive NMR (1H, 13C, COSY, HMQC, HMBC, and NOESY) and EI-MS studies. Compound 1 exhibited cytotoxic activity against the SK-Hep 1 cell line.

  20. Role of Y in the oxidation resistance of CrAlYN coatings

    Energy Technology Data Exchange (ETDEWEB)

    Domínguez-Meister, S.; El Mrabet, S. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda., Américo Vespucio 49, Sevilla 41092 (Spain); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Inés de la Cruz 3, Cantoblanco 28049 (Spain); Mariscal, A.; Jiménez de Haro, M.C.; Justo, A. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda., Américo Vespucio 49, Sevilla 41092 (Spain); Brizuela, M. [TECNALIA, Mikeletegui Pasealekua, 2, Donostia-San Sebastián 20009 (Spain); Rojas, T.C. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda., Américo Vespucio 49, Sevilla 41092 (Spain); Sánchez-López, J.C., E-mail: jcslopez@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda., Américo Vespucio 49, Sevilla 41092 (Spain)

    2015-10-30

    Highlights: • The oxidation behavior of CrAlYN films (Al < 10 at.%) depends on the Al/Y distribution. • ∼4 at.% Y enhances the oxidation resistance up to 1000 °C of CrAlYN-coated M2 steels. • Controlled inward oxygen diffusion affects positively the film oxidation resistance. • Mixed Al–Y oxides appear to block the diffusion of elements from the substrate. • Yttrium modifies the passivation layer composition by increasing the Al/Cr ratio. - Abstract: CrAlYN coatings with different aluminum (4–12 at.%) and yttrium (2–5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N{sub 2} mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr{sub 2}N, and a more effective Fe and C blocking.

  1. Structural, electronic and magnetic properties of LaCr2Si2C: Ab initio calculation, mean field approximation and Monte-Carlo simulation

    Science.gov (United States)

    Endichi, A.; Zaari, H.; Benyoussef, A.; El Kenz, A.

    2018-06-01

    The magnetic behavior of LaCr2Si2C compound is investigated in this work, using first principle methods, Monte Carlo simulation (MCS) and mean field approximation (MFA). The structural, electronic and magnetic properties are described using ab initio method in the framework of the Generalized Gradient Approximation (GGA), and the Full Potential-Linearized Augmented Plane Wave (FP-LAPW) method implemented in the WIEN2K packages. We have also computed the coupling terms between magnetic atoms which are used in Hamiltonian model. A theoretical study realized by mean field approximation and Monte Carlo Simulation within the Ising model is used to more understand the magnetic properties of this compound. Thereby, our results showed a ferromagnetic ordering of the Cr magnetic moments below the Curie temperature of 30 K (Tc magnetization, the energy, the specific heat and the susceptibility. This material shows the small sign of supra-conductivity; and future researches could be focused to enhance the transport and magnetic properties of this system.

  2. Structure of an extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83

    Energy Technology Data Exchange (ETDEWEB)

    Vanhaverbeke, C.; Bosso, C.; Colin-Morel, P.; Gey, C.; Heyraud, A. [Centre de Recherches sur les Macromolecules Vegetales, CNRS and Universite Joseph Fourier, B.P.53, F-38041 Grenoble (France); Gamar-Nourani, L.; Blondeau, K.; Simonet, J.-M. [Institut de Genetique et Microbiologie, Laboratoire de Genetique Moleculaire des Bacteries d' Interet Industriel, CNRS URA 2225, Batiment 360, Universite de Paris Sud, F-91405 Orsay (France)

    1998-12-31

    The extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83 was found to be composed of d-glucose and d-galactose in a molar ratio of 2:3. The primary structure of the polysaccharide was shown by sugar analysis, methylation analysis, FABMS, partial acid hydrolysis and nuclear magnetic resonance (NMR) spectroscopy to consist of a pentasaccharide repeating unit having the following structure:-3)-{alpha}-d-Glcp-(1-2)-{beta}-d-Galf-(1-6)-{alpha}-d-Galp-(1-6) -{alpha}-d-Glcp-(1-3)-{beta}-d-Galf-(1-. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  3. Structure of an extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83

    International Nuclear Information System (INIS)

    Vanhaverbeke, C.; Bosso, C.; Colin-Morel, P.; Gey, C.; Heyraud, A.; Gamar-Nourani, L.; Blondeau, K.; Simonet, J.-M.

    1998-01-01

    The extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83 was found to be composed of d-glucose and d-galactose in a molar ratio of 2:3. The primary structure of the polysaccharide was shown by sugar analysis, methylation analysis, FABMS, partial acid hydrolysis and nuclear magnetic resonance (NMR) spectroscopy to consist of a pentasaccharide repeating unit having the following structure:-3)-α-d-Glcp-(1-2)-β-d-Galf-(1-6)-α-d-Galp-(1-6) -α-d-Glcp-(1-3)-β-d-Galf-(1-. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Mol 7C/6

    International Nuclear Information System (INIS)

    Aberle, J.; Schleisiek, K.; Schmuck, I.; Schmidt, L.; Romer, O.; Weih, G.

    1995-01-01

    The Mol 7C/6 coolant blockage experiment in the Belgian BR2 reactor yielded results different from Mol 7C experiments with low burnup pins: At 10% burnup local failure is not self-limiting, but requires active systems for detection and scram. The Mol 7C series was finished in 1991. In each of the test bundles Mol 7C/4, /5 and /6, 30 Mk I pins pre-irradiated in KNK II were used. The central blockage consisted of enriched UO 2 covering 30 percent of the bundle cross-section, with a height of 40 mm. The most important system for timely detection of coolant blockages of the type studied in Mol 7C/6 is based on DND. (orig.)

  5. Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys

    International Nuclear Information System (INIS)

    Novakovic, R

    2011-01-01

    The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi 2 composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al 8 Cr 5 and CrNi 2 chemical complexes, respectively, as energetically favoured.

  6. Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys.

    Science.gov (United States)

    Novakovic, R

    2011-06-15

    The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi(2) composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al(8)Cr(5) and CrNi(2) chemical complexes, respectively, as energetically favoured.

  7. Crystal structure of the mixed-metal trisulfide BaCu1/3Ta2/3S3

    Directory of Open Access Journals (Sweden)

    Kejun Bu

    2017-05-01

    Full Text Available The mixed-metal title compound, BaCu1/3Ta2/3S3 [barium copper(II tantalum(V trisulfide], was prepared through solid-state reactions. The crystal structure adopts the BaTaS3 structure type and consists of face-sharing [MS6] (M = Ta,Cu octahedra (point-group symmetry -3m. that are condensed into infinite chains along [001]. Adjacent chains are linked through the barium cations (site symmetry -6m2, which exhibit a coordination number of twelve. The M site is occupied by 2/3 of TaV and 1/3 of CuII, whereby the average M—S distances are slightly longer than those of ordered BaTaS3. The classical charge balance of the title compound can be represented by [Ba2+] [(Ta/Cu4+] [S2−]3.

  8. Chlamydomonas DYX1C1/PF23 is essential for axonemal assembly and proper morphology of inner dynein arms.

    Directory of Open Access Journals (Sweden)

    Ryosuke Yamamoto

    2017-09-01

    Full Text Available Cytoplasmic assembly of ciliary dyneins, a process known as preassembly, requires numerous non-dynein proteins, but the identities and functions of these proteins are not fully elucidated. Here, we show that the classical Chlamydomonas motility mutant pf23 is defective in the Chlamydomonas homolog of DYX1C1. The pf23 mutant has a 494 bp deletion in the DYX1C1 gene and expresses a shorter DYX1C1 protein in the cytoplasm. Structural analyses, using cryo-ET, reveal that pf23 axonemes lack most of the inner dynein arms. Spectral counting confirms that DYX1C1 is essential for the assembly of the majority of ciliary inner dynein arms (IDA as well as a fraction of the outer dynein arms (ODA. A C-terminal truncation of DYX1C1 shows a reduction in a subset of these ciliary IDAs. Sucrose gradients of cytoplasmic extracts show that preassembled ciliary dyneins are reduced compared to wild-type, which suggests an important role in dynein complex stability. The role of PF23/DYX1C1 remains unknown, but we suggest that DYX1C1 could provide a scaffold for macromolecular assembly.

  9. Study on structural and optical properties of α-(AlxCr1-x)2O3 (0 ≤ x ≤ 1) solid solutions

    Science.gov (United States)

    Jangir, Ravindra; Kumar, Dharmendra; Srihari, Velaga; Ganguli, Tapas

    2018-04-01

    We report on structural and optical properties for ternary α-(AlxCr1-x)2O3 (0 ≤ x ≤ 1) solid solutions synthesized by using solid sate reaction method. Single R-3c phase was obtained for the Aluminum composition of 0 ≤ x ≤ 1. Due to difference in the ionic radia of Al3+ and Cr3+, in plane lattice parameter showed deviation from the vegard's law. Optical absorption spectra for the solid solutions showed a blue shift of ˜ 0.5 eV in the optical gap. It has also been observed that Cr 3d level shifted towards the O 2p level in the valance band which indicates the enhancement of hybridization in the d and p levels, which is related to the delocalization of hole states, responsible for p-type conduction in wide band gap semiconductors. The results suggests that ternary α-(AlxCr1-x)2O3 (0 ≤ x ≤ 1) can be useful in the field of UV transparent electronics and UV photodetectors.

  10. Investigation of the structural and hydrogenation properties of disordered Ti-V-Cr-Mo BCC solid solutions

    International Nuclear Information System (INIS)

    Raufast, C.; Planté, D.; Miraglia, S.

    2014-01-01

    Highlights: • Materials synthesis and structural analysis of selected compositions of TiVCr(Mo) bcc samples. • Extraction of the thermodynamics relevant parameters for hydride formation and dissociation state of Ti 0.3 V 1.7 Cr 0.7 Mo 0.3 sample. • Discussion of the hydrides practicability. - Abstract: Selected compositions in the Ti-Cr-V-Mo system (with the BCC structure-type) have been synthesized and characterized for structural (crystalline structure, solidification microstructure) and thermodynamic properties (equilibrium and reversible hydrogen storage capacity). We present as well the effect of co-melting with a so-called activating phase that results in a secondary phase development and a subsequent enhancement of the hydrogen sorption kinetics. Ageing properties and applicability of such materials for hybrid hydrogen storage systems are also discussed

  11. Thermal convection loop experiments and analysis of mass transport process in Lithium/Fe-12Cr-1MoVW systems

    International Nuclear Information System (INIS)

    Bell, G.E.C.

    1988-01-01

    Lithium is an attractive coolant and breeder material for first- generation fusion reactor blankets. The compatibility of lithium with structural alloys, in the form of mass transport and deposition, may impose restrictions on blanket operating parameters such as temperature and lithium purity. A ferritic steel, such as Fe-12CrlMoVW, is a candidate for use as a structural alloy in a self-cooled lithium blanket design. Experimental data on mass transport in lithium/Fe-12CrlMoVW were obtained from two thermal convection loops which spanned the fusion relevant temperature range; one operated from 360 to 505/degree/C for 3040 hours and the other from 525 to 655/degree/C for 2510 hours. The experimental effort was supported by analysis of the mechanisms and processes of mass transport and deposition. It was found that mass transport and deposition, as measured by specimen weight change, were not simple functions of temperature for the entire temperature range investigated. The mass transfer behavior and surface morphology at low temperatures were dominated by impurity reactions of nitrogen and carbon in the lithium with the steel. In the experiment between 360 and 505/degree/C, nitrogen levels were sufficient below 450/degree/C to allow the formation of the adherent, protective corrosion product Li 9 CrN 5 . Weight losses in the 360 to 505/degree/C experiment were insensitive to temperature below 450/degree/C. Between 450 and 505/degree/C, the precipitation of carbon in the form of chromium-rich M 23 C 6 (M = Fe or Cr) carbides, due to the formation of Li 9 CrN 5 and corresponding release of carbon, resulted in weight gains for the highest temperature specimens in the experiment. 98 refs., 83 figs., 9 tabs

  12. A new triclinic modification of the pyrochlore-type KOs2O6 superconductor

    International Nuclear Information System (INIS)

    Katrych, S.; Gu, Q.F.; Bukowski, Z.; Zhigadlo, N.D.; Krauss, G.; Karpinski, J.

    2009-01-01

    A new modification of KOs 2 O 6 , the representative of a new structural type (Pearson symbol aP18, a=5.5668(1) A, b=6.4519(2) A, c=7.2356(2) A, α=65.377(3) o , β=70.572(3) o , γ=75.613(2) o space group P-1, no. 2 was synthesized employing high pressure technique. Its structure was determined by single-crystal X-ray diffraction. The structure can be described as two OsO 6 octahedral chains relating to each other through inversion and forming big voids with K atoms inside. Quantum chemical calculations were performed on the novel compound and structurally related cubic compound. High-pressure X-ray study showed that cubic KOs 2 O 6 phase was stable up to 32.5(2) GPa at room temperature. - Graphical abstract: A new modification of KOs 2 O 6 , the representative of a new structural type (Pearson symbol aP18, a=5.5668(1) A, b=6.4519(2) A, c=7.2356(2) A, α=65.377(3) o , β=70.572(3) o , γ=75.613(2) o space group P-1, no. 2 was synthesized employing high pressure technique. The structure can be described as two OsO 6 octahedral chains relating to each other through inversion and forming big voids with K atoms inside

  13. Oxidation induced crack healing of Cr2(Al,Si)C max phase ceramic

    NARCIS (Netherlands)

    Shen, L.; Li, S.B.; Van der Zwaag, S.; Sloof, W.G.

    2013-01-01

    The oxidation crack healing of Cr2AlC and Cr2(Al,Si)C was studied and compared with known healing of Ti2AlC. The oxidation induced crack healing of Ti2AlC is relatively fast and leads to full strength recovery, but the oxidation product contains besides ?-Al2O3 also undesired TiO2. However, when

  14. Interleukin 6 -174(G>C) gene polymorphism is related to celiac disease and autoimmune thyroiditis coincidence in diabetes type 1 children.

    Science.gov (United States)

    Myśliwiec, Małgorzata; Myśliwska, Jolanta; Zorena, Katarzyna; Balcerska, Anna; Malinowska, Ewa; Wiśniewski, Piotr

    2008-10-01

    The aim of the study was to assess the relationship between IL-6 gene polymorphism at -174(G>C) and the coincidence of celiac and autoimmune thyroid diseases with type 1 diabetes mellitus (DM1) in children. 200 children with DM1 aged 13.23+/-3.54 years and 172 healthy controls were analyzed. The IL-6 gene -174(G>C) polymorphism at the promoter region of the gene was analyzed by the PCR-RFLP method. The genotype distribution was significantly different in diabetic children as compared to the healthy controls (p=0.01). In DM1 patients GC heterozygotes were the most common (52.5%), while CC homozygotes accuted for 29% and GG homozygotes only for 18% of cases. In contrast, GG homozygotes were much more frequent among healthy children (31%). Besides, the GG homozygotes were significantly more frequent among diabetic children with celiac disease (p=0.04) in relation to those without autoimmune complications. In children with autoimmune thyroiditis, the distribution of the IL-6 genotypes was similar to that seen in diabetic patients without autoimmune complications (p=0.24). The results of our study suggest that the diabetic children, who have IL-6 gene -174GG genotype may have an increased risk for celiac disease development.

  15. Structural, optical and magnetic properties of Cr doped SnO{sub 2} nanoparticles stabilized with polyethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Subramanyam, K.; Sreelekha, N. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Murali, G. [Department of BIN Fusion Technology and Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Reddy, D. Amaranatha [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2014-12-01

    Pure and Cr (1, 3, 5 and 7 at%) doped SnO{sub 2} nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO{sub 2} nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4{sub 2}/mnm) of SnO{sub 2}. The peak positions with Cr concentration shifted to higher 2θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8–10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O–Sn–O entities. Further it revealed that the undoped and as well as Cr doped SnO{sub 2} nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO{sub 2} nanoparticles.

  16. Electron microscopy characterization of mechanically alloyed and hot consolidates Cu-Cr3C2 particles

    Directory of Open Access Journals (Sweden)

    López, M.

    2005-08-01

    Full Text Available Mechanically alloyed copper-ceramic composites have been obtained with the purpose of studying their use as copper-based material for electrical equipment. For high-temperature applications, dispersion-strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivity, mechanical strength retention and microstructural stability. In this work, powder mixtures of pure copper with 2 vol % Cr3C2, milled during 4, 6, 10, 12 and 15 h in a high-energy planetary balls mill under argon atmosphere, were consolidated by hot isostatic pressing, applying a pressure of 100 MPa at 1073 K for two hours, to obtain materials with a fine microstructure. The Cu-Cr3C2 alloys were studied by scanning electron microscopy (SEM, electron microprobe (EPMA and transmission electron microscopy (TEM. Mechanical properties and electrical conductivity were also studied. The average tensile strength and electrical conductivity were found to be 500 MPa and 50 % IACS, respectively. The Cr3C2 ceramics show good stability during hot consolidation. Contributing to a further strengthening of the alloy during the hot consolidation, uniformly-distributed Fe-carbide particles of nanometric size precipitated in the copper matrix. Fe-Cr oxycarbides formed in the interphase between Cr3C2 particles and the copper matrix cause the low ductility of Cu-Cr3C2 alloys. Said particles are attributed to impurities/contamination generated from the milling process.

    Se obtuvieron aleaciones compuestas de Cu-Cr3C2, aleadas mecánicamente, para estudiar futuras aplicaciones en componentes eléctricos. A altas temperaturas, las aleaciones de base cobre reforzadas por dispersión, son atractivas por su excelente conductividad térmica y eléctrica, propiedades mecánicas y estabilidad microstructural. En este estudio

  17. The determination of hexavalent chromium (Cr6+) in electronic and electrical components and products to comply with RoHS regulations

    International Nuclear Information System (INIS)

    Hua, L.; Chan, Y.C.; Wu, Y.P.; Wu, B.Y.

    2009-01-01

    Toxicity of hexavalent chromium (Cr 6+ ) was focused on with a publication of EU RoHS directive, a novel method to determine hexavalent chromium is developed. It is a combination of energy dispersion X-ray fluorescence spectrometry (EDXRF), spot test, alkali digestion and UV-vis spectrophotometric analysis. First, by EDXRF screening, the presence or absence of element Cr was established. Spot test was followed to identify the valent state of chromium because Cr 6+ and Cr 3+ normally coexist. After alkali digestion, Cr(VI) was separated without an undersired Cr(VI)-Cr(III) interconversions. With a color reagent (DPC) to chelated with Cr(VI), the solution was finally detected by a UV-vis spectrophotometer at a wavelength of 540 nm which is the basis of analyzing Cr(VI) quantitatively. Some parameters affecting analyses were studied. It was found that when pH in the final solution was 2.0, the extraction time was 60 min, the extraction temperature was 90 deg. C, pH during the extraction process was 7.5-8.5, and a mixed buffer solution (0.5 M K 2 HPO 4 /0.5 M KH 2 PO 4 ) was added up to 1 ml, colorimetric reagent was added to 2 ml, it is optimal for extraction. Under this condition, interferences from Fe 3+ , Pb 2+ , Ag + , etc., were overcome. It was also found that the curves are rectilinear in the range of 0-500 μg l -1 , the correlation coefficient is up to 0.999924, and the recovery rates are more than 85%, the Cr(III)-DPCO complex can be kept stable for 24 h with a relative humidity (RH) range of 60-90%, and a temperature range of 5-40 deg. C. So it can be concluded that the proposed method has a good sensitivity and high precision. It is a more convincing and reliable method due to its relative standard deviation (R.S.D.) <1% after six replicate determinations of Cr(VI) in an Fe-Ni alloy sample

  18. Influence of Cr doping on the stability and structure of small cobalt oxide clusters

    Energy Technology Data Exchange (ETDEWEB)

    Tung, Nguyen Thanh; Lievens, Peter; Janssens, Ewald, E-mail: ewald.janssens@fys.kuleuven.be [Laboratory of Solid-State Physics and Magnetism, KU Leuven, B-3001 Leuven (Belgium); Tam, Nguyen Minh; Nguyen, Minh Tho [Department of Chemistry, KU Leuven, B-3001 Leuven (Belgium)

    2014-07-28

    The stability of mass-selected pure cobalt oxide and chromium doped cobalt oxide cluster cations, Co{sub n}O{sub m}{sup +} and Co{sub n−1}CrO{sub m}{sup +} (n = 2, 3; m = 2–6 and n = 4; m = 3–8), has been investigated using photodissociation mass spectrometry. Oxygen-rich Co{sub n}O{sub m}{sup +} clusters (m ⩾ n + 1 for n = 2, 4 and m ⩾ n + 2 for n = 3) prefer to photodissociate via the loss of an oxygen molecule, whereas oxygen poorer clusters favor the evaporation of oxygen atoms. Substituting a single Co atom by a single Cr atom alters the dissociation behavior. All investigated Co{sub n−1}CrO{sub m}{sup +} clusters, except CoCrO{sub 2}{sup +} and CoCrO{sub 3}{sup +}, prefer to decay by eliminating a neutral oxygen molecule. Co{sub 2}O{sub 2}{sup +}, Co{sub 4}O{sub 3}{sup +}, Co{sub 4}O{sub 4}{sup +}, and CoCrO{sub 2}{sup +} are found to be relatively difficult to dissociate and appear as fragmentation product of several larger clusters, suggesting that they are particularly stable. The geometric structures of pure and Cr doped cobalt oxide species are studied using density functional theory calculations. Dissociation energies for different evaporation channels are calculated and compared with the experimental observations. The influence of the dopant atom on the structure and the stability of the clusters is discussed.

  19. Electronic structure of metastable bcc Cu–Cr alloy thin films: Comparison of electron energy-loss spectroscopy and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Liebscher, C.H.; Freysoldt, C. [Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf (Germany); Dennenwaldt, T. [Institute of Condensed Matter Physics and Interdisciplinary Center for Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Harzer, T.P.; Dehm, G. [Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf (Germany)

    2017-07-15

    Metastable Cu–Cr alloy thin films with nominal thickness of 300 nm and composition of Cu{sub 67}Cr{sub 33} (at%) are obtained by co-evaporation using molecular beam epitaxy. The microstructure, chemical phase separation and electronic structure are investigated by transmission electron microscopy (TEM). The thin film adopts the body-centered cubic crystal structure and consists of columnar grains with ~50 nm diameter. Aberration-corrected scanning TEM in combination with energy dispersive X-ray spectroscopy confirms compositional fluctuations within the grains. Cu- and Cr-rich domains with composition of Cu{sub 85}Cr{sub 15} (at%) and Cu{sub 42}Cr{sub 58} (at%) and domain size of 1–5 nm are observed. The alignment of the interface between the Cu- and Cr-rich domains shows a preference for {110}-type habit plane. The electronic structure of the Cu–Cr thin films is investigated by electron energy loss spectroscopy (EELS) and is contrasted to an fcc-Cu reference sample. The experimental EEL spectra are compared to spectra computed by density functional theory. The main differences between bcc-and fcc-Cu are related to differences in van Hove singularities in the electron density of states. In Cu–Cr solid solutions with bcc crystal structure a single peak after the L{sub 3}-edge, corresponding to a van Hove singularity at the N-point of the first Brillouin zone is observed. Spectra computed for pure bcc-Cu and random Cu–Cr solid solutions with 10 at% Cr confirm the experimental observations. The calculated spectrum for a perfect Cu{sub 50}Cr{sub 50} (at%) random structure shows a shift in the van Hove singularity towards higher energy by developing a Cu–Cr d-band that lies between the delocalized d-bands of Cu and Cr. - Highlights: • Compositional fluctuations on the order of 1–5 nm in Cu- and Cr-rich domains are observed. • EELS determines a single van Hove singularity for bcc Cu–Cr solid solutions. • The electronic structure is dominated by d

  20. Structure of multilayered Cr(Al)N/SiO{sub x} nanocomposite coatings fabricated by differential pumping co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Masahiro [JEOL USA Inc., 11 Dearborn Road, Peabody, Massachusetts 01960 (United States); Nose, Masateru [Faculty of Art and Design, University of Toyama, 180 Futagami-machi, Takaoka 933-8588 (Japan); Onishi, Ichiro [JEOL Ltd. 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Shiojiri, Makoto [Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

    2013-11-11

    A Cr(Al)N/38 vol. % SiO{sub x} hard coating was prepared on a (001) Si substrate at 250 °C in a differential pumping co-sputtering system, which has two chambers for radio frequency (RF) sputtering and a substrate holder rotating on the chambers. The composite coating was grown by alternate sputter-depositions from CrAl and SiO{sub 2} targets with flows of N{sub 2}+Ar and Ar at RF powers of 200 and 75 W, respectively, on transition layers grown on the substrate. Analytical electron microscopy reveled that the Cr(Al)N/SiO{sub x} coating had a multilayered structure of Cr(Al)N crystal layers ∼1.6 nm thick and two-dimensionally dispersed amorphous silicon oxide (a-SiO{sub x}) particles with sizes of ∼1 nm or less. The a-SiO{sub x} particles were enclosed with the Cr(Al)N layers. The coating had a low indentation hardness of ∼25 GPa at room temperature, due to a high oxide fraction of 38 vol. % and a low substrate rotational speed of 1 rpm. Faster rotation and lower oxide fraction would make a-SiO{sub x} particles smaller, resulting in the formation of Cr(Al)N crystal including the very fine a-SiO{sub x} particles with small number density. They would work as obstacles for the lattice deformation of the Cr(Al)N crystals. We have fabricated a superhard coating of Cr(Al)N/17 vol. % SiO{sub x} with a hardness of 46 GPa prepared at 12 rpm.

  1. Synthesis, spectroscopic, structural and thermal characterizations of [(C7H6NO42TeBr6·4H2O

    Directory of Open Access Journals (Sweden)

    S. Smaoui

    2018-02-01

    Full Text Available Tellurium (IV complexes with pyridine-2,6-dicarboxylate ligand were synthesized by slow evaporation from aqueous solutions yielding a new compound: [(C7H6NO42TeBr6·4H2O]. The structure of this compound was solved and refined by single-crystal X-ray diffraction. The compound is centrosymmetric P21/c (N°: 14 with the parameters a = 8.875(5 Å, b = 15.174(5 Å, c = 10.199(5 Å, β = 94.271° (5 and Z = 2. The structure consists of isolated H2O, isolated [TeBr6]2− octahedral anions and (pyridine-2,6-dicarboxylate [C7H6NO4]+ cations. The stability of the structure was ensured by ionic and hydrogen bonding contacts (N–H⋯Br and O–H⋯Br and Van-Der Walls interaction. The thermal decomposition of the compound was studied by thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The FTIR and Raman spectroscopy at different temperatures confirm the existence of vibrational modes that correspond to the organic, inorganic and water molecular groups. Additionally, the UV–Vis diffuse reflectance spectrum was recorded in order to investigate the band gap nature. The measurements show that this compound exhibits a semiconducting behavior with an optical band gap of 2.66 eV.

  2. Removal of Cr{sup 6+} from wastewater via adsorption with high-specific-surface-area nitrogen-doped hierarchical porous carbon derived from silkworm cocoon

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junting; Zhang, Zhengping; Ji, Jing; Dou, Meiling, E-mail: douml@mail.buct.edu.cn; Wang, Feng, E-mail: wangf@mail.buct.edu.cn

    2017-05-31

    Highlights: • The nitrogen-doped hierarchical porous carbon was prepared from silkworm cocoon. • The NHPC possesses a unique porous structure and a high specific surface area. • The NHPC presents superior adsorption performance for Cr (VI). • The NHPC exhibits an excellent recyclability for the removal of Cr (VI). - Abstract: The development of highly efficient adsorbents is an effective way to remove Cr{sup 6+} from wastewater for environment protection. Herein, a high-specific-surface-area nitrogen-doped hierarchical porous carbon (NHPC) derived from silkworm cocoon was synthesized and applied as an efficient adsorbent for the removal of Cr{sup 6+} from wastewater. The resultant NHPC possesses a specific surface area as high as 3134 m{sup 2} g{sup −1} and a unique hierarchical porous structure with a large number of small mesopores (2–4 nm) and micropores (0.8–2 nm) embedded in the sidewall of bowl-like macropores (200–300 nm), in which sufficient exposure of adsorption sites and high-flow transfer of Cr{sup 6+} ions can be achieved. As a result, the NHPC exhibits a remarkable adsorption performance with a larger adsorption capacity (366.3 mg g{sup −1}), a higher adsorption rate (4 × 10{sup −2} g mg{sup −1} min{sup −1}) and a superior recyclability in comparison with the commercial adsorbent (Norit CGP). Thermodynamic and kinetic analyses indicate that the adsorption process is spontaneous and endothermic, which fits well with the pseudo-second-order kinetic model and Langmuir isotherm model. This biomass-based porous carbon with well-defined hierarchical porous structure can be applied as a promising adsorbent for the removal of Cr{sup 6+} from wastewater.

  3. Size-dependent magnetic and structural properties of CoCrFeO4 nano-powder prepared by solution self-combustion

    Science.gov (United States)

    Sijo, A. K.; Dutta, Dimple P.

    2018-04-01

    The study reports the tuning of magnetic and structural properties of nano-sized CoCrFeO4 via post-annealing treatment. CoCrFeO4 nano-powder has been prepared by solution self-combustion method. The structural and magnetic properties have been studied over a range of annealing temperatures (300-900 °C). The formation of the phase pure CoCrFeO4 spinel has been confirmed from powder XRD analysis. The crystallite size is observed to increase with an increase in annealing temperature. On annealing, the value of magnetic parameters-remanence, coercivity and saturation magnetization have enhanced. All the samples exhibit irreversibility at low-temperature measurements.

  4. Effect of carbon on the microstructure, mechanical properties and metal ion release of Ni-free Co-Cr-Mo alloys containing nitrogen.

    Science.gov (United States)

    Mori, Manami; Yamanaka, Kenta; Kuramoto, Koji; Ohmura, Kazuyo; Ashino, Tetsuya; Chiba, Akihiko

    2015-10-01

    This paper investigated the effect of carbon addition on the microstructure and tensile properties of Ni-free biomedical Co-29Cr-6Mo (mass%) alloys containing 0.2 mass% nitrogen. The release of metal ions by the alloys was preliminarily evaluated in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid, after which samples with different carbon contents were subjected to hot rolling. All specimens were found to primarily consist of a γ-phase matrix due to nitrogen doping, with only the volume fraction of M23C6 increasing with carbon concentration. Owing to the very fine size of these carbide particles (less than 1 μm), which results from fragmentation during hot rolling, the increased formation of M23C6 increased the 0.2% proof stress, but reduced the elongation-to-failure. Carbon addition also increased the amount of Co and Cr released during static immersion; Co and Cr concentrations at the surfaces, which increased with increasing the bulk carbon concentrations, possibly enhanced the metal ion release. However, only a very small change in the Mo concentration was noticed in the solution. Therefore, it is not necessarily considered a suitable means of improving the strength of biomedical Co-Cr-Mo alloys, even though it has only to date been used in this alloy system. The results of this study revealed the limitations of the carbon strengthening and can aid in the design of biomedical Co-Cr-Mo-based alloys that exhibit the high durability needed for their practical application. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Study of nucleation, growth and coarsening of precipitates in a novel 9%Cr heat resistant steel: Experimental and modeling

    International Nuclear Information System (INIS)

    Prat, O.; García, J.; Rojas, D.; Sanhueza, J.P.; Camurri, C.

    2014-01-01

    Nucleation, growth and coarsening of three different precipitates (NbC, M 23 C 6 and V(C,N)) in a novel 9%Cr heat resistant steel designed by the authors were investigated. The microstructure evolution after tempering (780 °C/2 h) and after creep (650 °C/100 MPa) was characterized using transmission electron microscopy in the scanning mode (STEM). Thermodynamic and kinetic modeling was carried out using the softwares Thermo-Calc, DICTRA and TC-PRISMA. The Thermo-Calc software predicted formation of NbC, V(C,N) and M 23 C 6 carbides at the tempering temperature of 780 °C. STEM investigations revealed that M 23 C 6 precipitated on prior austenite grain boundaries and lath or block boundaries whereas NbC and V(C,N) were located within sub-grains. Simulations by TC-PRISMA showed that M 23 C 6 , NbC and V(C,N) particles nucleation begins as soon as the tempering treatment starts and it is completed in a very short time, reaching the equilibrium volume fraction after 40 s for M 23 C 6 , 100 s for NbC and 80 s for V(C,N). Best agreement between simulations and experimental investigations was found for low interfacial energy values of 0.1 J m −2 . Both STEM measurements as well as DICTRA simulations indicate very low coarsening rate for both kind of precipitates. Creep tests up to 4000–5000 h suggest that this special combination of NbC, V(C,N) and M 23 C 6 may provide increased pinning of dislocations reducing boundary migration therefore enhancing creep strength. - Highlights: • Nucleation, growth and coarsening of NbC and M 23 C 6 precipitates were investigated. • The microstructure was characterized using transmission electron microscopy (STEM). • Modeling was carried out using the softwares Thermo-Calc, DICTRA and TC-PRISMA. • M 23 C 6 and NbC nucleation begins as soon as the solution treatmentinitiates. • Best agreement modeling/experiments was found for low interfacial energy values of 0.1 J m −2

  6. Temperature- and pressure-induced lattice distortion in CdCr2-xGaxSe4 (x = 0, 0.06, and 0.12)

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, Leif; Olsen, J.S.

    2002-01-01

    Structural changes in the cubic spinels CdCr2-xGaxSe4 have been studied by means of single-crystal x-ray diffraction at low temperature and energy-dispersive diffraction in a diamond-anvil cell at high pressure. In stoichiometric samples (x = 0), a spontaneous magnetostriction reduces the thermal...... expansion coefficient from 6.7 x 10(-6) K-1 in the paramagnetic phase to 2.2 x 10(-6) K-1 in the ferromagnetic phase (T-C = 130 K). In the samples with Ga3+ admixtures (x = 0.06 and 0.12), a slight structural distortion causes an order-disorder-type phase transition at T-d approximate to 285 K connected...

  7. Heterocyclic Analogues of Xanthone and Xanthione. 1H-Pyrano[2,3-c:6,5-c]dipyrazol-4(7H-ones and Thiones: Synthesis and NMR Data

    Directory of Open Access Journals (Sweden)

    Wolfgang Holzer

    2010-09-01

    Full Text Available The synthesis of the title compounds is described. Reaction of 1-substituted 2-pyrazolin-5-ones with 5-chloro-1-phenyl-1H-pyrazole-4-carbonyl chloride or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbonyl chloride, respectively, using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-heteroaroylpyrazol-5-ols, which were cyclized into 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H-ones by treatment with K2CO3/DMF. The latter were converted into the corresponding thiones upon reaction with Lawesson’s reagent. Detailed NMR spectroscopic investigations (1H, 13C, 15N of the ring systems and their precursors are presented.

  8. Neonatal Hyperbilirubinemia in infants with G6PD c.563C > TVariant

    Directory of Open Access Journals (Sweden)

    Moiz Bushra

    2012-08-01

    Full Text Available Abstract Background There is a strong correlation between glucose-6-phosphate dehydrogenase (G6PD deficiency and neonatal hyperbilirubinemia with a rare but potential threat of devastating acute bilirubin encephalopathy. G6PD deficiency was observed in 4–14% of hospitalized icteric neonates in Pakistan. G6PD c.563C > T is the most frequently reported variant in this population. The present study was aimed at evaluating the time to onset of hyperbilirubinemia and the postnatal bilirubin trajectory in infants having G6PD c.563C > T. Methods This was a case–control study conducted at The Aga Khan University, Pakistan during the year 2008. We studied 216 icteric male neonates who were re-admitted for phototherapy during the study period. No selection was exercised. Medical records showed that 32 were G6PD deficient while 184 were G6PD normal. Each infant was studied for birth weight, gestational age, age at the time of presentation, presence of cephalhematoma, sepsis and neurological signs, peak bilirubin level, age at peak bilirubin level, days of hospitalization, whether phototherapy or exchange blood transfusion was initiated, and the outcome. During hospital stay, each baby was tested for complete blood count, reticulocyte count, ABO and Rh blood type, direct antiglobulin test and quantitative G6PD estimation [by kinetic determination of G6PDH]. G6PDgenotype was analyzed in 32 deficient infants through PCR-RFLP analysis and gene sequencing. Results G6PD variants c.563C > T and c.131 C > G were observed in 21 (65% and three (9% of the 32 G6PD deficient infants, respectively. DNA of eight (25% newborns remained uncharacterized. In contrast to G6PD normal neonates, infants with c.563C > T variant had significantly lower enzyme activity (mean ± 1SD; 0.3 ± 0.2 U/gHb vs. 14.0 ± 4.5 U/gHb, p p = 0.008 which peaked earlier after birth (mean ± 1SD 2.9 ± 1.6 vs. 4.3 ± 2.3 days, p = 0.007. No statistically significant

  9. C_6_0"3"- versus C_6_0"4"- /C_6_0"2"- - synthesis and characterization of five salts containing discrete fullerene anions

    International Nuclear Information System (INIS)

    Boeddinghaus, M. Bele; Klein, Wilhelm; Wahl, Bernhard; Faessler, Thomas F.; Jakes, Peter; Eichel, Ruediger A.

    2014-01-01

    Five new compounds, [Rb(18crown-6)]_3[C_6_0] (1), [Rb(18crown-6)]_6[C_6_0]_2(C_3H_7NO)_2(C_4H_8O)_2 (2), [Rb(benzo18crown-6)]_6[C_6_0]_2(C_2H_8N_2)_5 (3), [Cs(benzo18crown-6)]_3C_6_0(C_2H_8N_2)_2 (4), and [Cs_3(benzo18crown-6)_5]C_6_0(C_2H_8N_2)_(_4_._5_+_x_) (5) were synthesized and characterized by single-crystal X-ray structure determination. All compounds contain discrete C_6_0 anions, which are ordered in 1, 2, and 4, where direct cation-anion contacts occur. The unit cells of 1 and 2 contain two independent fullerides, which coordinate to the rubidium atoms either of two or of four [Rb(18crown-6)] units. Owing to the presence of differently coordinated fullerene units in compounds 1 and 2, a possible disproportionation of C_6_0"3"- into C_6_0"2"- and C_6_0"4"- anions is discussed. In 3 and 4 the C_6_0 anions are coordinated by three Rb and Cs atoms, respectively. In all compounds the average charge of the anion is -3. Magnetic data reveal a doublet spin state for 3. The EPR spectra are discussed for compounds 3 and 5. The role of a dynamic Jahn-Teller distortion is discussed, and we report the first IR spectroscopic data of fullerene trianions, which have been obtained in solution. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Effects of Structured Versus Usual Care on Renal Endpoint in Type 2 Diabetes: The SURE Study

    Science.gov (United States)

    Chan, Juliana C.; So, Wing-Yee; Yeung, Chun-Yip; Ko, Gary T.; Lau, Ip-Tim; Tsang, Man-Wo; Lau, Kam-Piu; Siu, Sing-Chung; Li, June K.; Yeung, Vincent T.; Leung, Wilson Y.; Tong, Peter C.

    2009-01-01

    OBJECTIVE Multifaceted care has been shown to reduce mortality and complications in type 2 diabetes. We hypothesized that structured care would reduce renal complications in type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 205 Chinese type 2 diabetic patients from nine public hospitals who had plasma creatinine levels of 150–350 μmol/l were randomly assigned to receive structured care (n = 104) or usual care (n = 101) for 2 years. The structured care group was managed according to a prespecified protocol with the following treatment goals: blood pressure triglyceride 500 μmol/l or dialysis). RESULTS Of these 205 patients (mean ± SD age 65 ± 7.2 years; disease duration 14 ± 7.9 years), the structured care group achieved better control than the usual care group (diastolic blood pressure 68 ± 12 vs. 71 ± 12 mmHg, respectively, P = 0.02; A1C 7.3 ± 1.3 vs. 8.0 ± 1.6%, P structured care (23.1%, n = 24) and usual care (23.8%, n = 24; NS) groups had similar end points, but more patients in the structured care group attained ≥3 treatment goals (61%, n = 63, vs. 28%, n = 28; P < 0.001). Patients who attained ≥3 treatment targets (n = 91) had reduced risk of the primary end point (14 vs. 34; relative risk 0.43 [95% CI 0.21–0.86] compared with that of those who attained ≤2 targets (n = 114). CONCLUSIONS Attainment of multiple treatment targets reduced the renal end point and death in type 2 diabetes. In addition to protocol, audits and feedback are needed to improve outcomes. PMID:19460913

  11. Manufacture of semifinished items of alloys V-4Ti-4Cr and V-10Ti-5Cr for use as a structural material in fusion applications

    International Nuclear Information System (INIS)

    Potapenko, M.M.; Drobishev, V.A.; Filkin, V.Y.; Gubkin, I.N.; Myasnikov, V.V.; Nikulin, A.D.; Shingarev, E.N.; Vedernikov, G.P.; Votinov, S.N.; Zurabov, V.S.; Zolotarev, A.B.

    1996-01-01

    Vanadium-titanium-chromium alloys are considered as structural materials with the most appropriate properties for fusion applications. However, the final ratio V-Ti-Cr in an alloy is not yet determined. On the one hand, it is offered to optimize structure on the basis of an alloy V-4Ti-4Cr. On the other hand, it is proposed that the optimum of total Ti and Cr content should be near 15%, and the Ti to Cr ratio should be 2:1. Melting, casting and processing by pressure of ingots of vanadium alloys V-4Ti-4Cr and V-10Ti-5Cr weighing as much as 50 kg are considered in the report. The ingots in diameters up to 130 mm were obtained by melting in vacuum-arc furnaces. Results on chemical uniformity and structure of the ingots are presented. A basic scheme of semifinished items manufacture is submitted. Rod and tube hot extrusion conditions are presented. A new technology for protection of ingot and billet surface from gases during hot processing is used to discard application of protective stainless steel and to lower temperature of processing. Sheet and tube products were made from extruded billets by cold rolling with intermediate heat treatment. The list of obtained products, including sheets 0.5-5 mm thick, rods 10-18 mm in diameter and tubes from 50 mm up to 6.0 mm in diameter is presented. The availability of large-scale ingots processing with weight above 300 kg is discussed. (orig.)

  12. /sup 51/Cr-bleomycin, a new oncophilic radiopharmaceutical. Pt. 1

    Energy Technology Data Exchange (ETDEWEB)

    Rembelska, M J; Liniecki, J

    1982-04-01

    A method was developed for labelling bleomycin with /sup 51/Cr. The complex was administered to mice (Swiss and C57-B1/6) bearing 5 transplantable tumours: Ehrlich ascites tumour, NK/Ly lymphoma, Lewis lung carcinoma, melanoma B-16, and Sarcoma 180. Activity concentration in neoplasms, blood and numerous organs was determined 12, 24 and 48 hrs after injection. An identical procedure was applied using /sup 58/Co-bleomycin as a reference oncophilic substance. Tumour/non-tumor ratios exceeding substantially unity were found for blood, muscle and bone indicating preferential accumulation of both /sup 58/Co and /sup 51/Cr in all the neoplasms tested. The ratios were lower (by a factor 2-3) for /sup 51/Cr than for /sup 58/Co; however, it is postulated that the gamma-quantum energy of /sup 51/Cr which is higher than that of the commonly used /sup 57/Co, should offset to some degree this difference when scintigraphic tumour detection in a patient is to be attempted. In conclusion, clinical trials with /sup 51/Cr-bleomycin, which is cheaper than its /sup 57/Co-counterpart, appear warranted.

  13. Rational construction of Z-scheme Ag_2CrO_4/g-C_3N_4 composites with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

    2016-01-01

    Highlights: • Novel visible-light driven Ag_2CrO_4/g-C_3N_4 composites were synthesized. • Ag_2CrO_4/g-C_3N_4 exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag_2CrO_4/g-C_3N_4 composites with different contents of Ag_2CrO_4 were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C_3N_4 and Ag_2CrO_4, the Ag_2CrO_4/g-C_3N_4 composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag_2CrO_4/g-C_3N_4 composite at a theoretical weight content of 8.0% Ag_2CrO_4 for the photodegradation of MO was 0.0068 min"−"1, which was 5.7 and 4.3 times higher than that of pure g-C_3N_4 and Ag_2CrO_4, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag_2CrO_4/g-C_3N_4 interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag_2CrO_4/g-C_3N_4 composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism was proposed. This work may be useful for the rational design of new types of Z-scheme photocatalysts and provide some illuminate insights into the Z-scheme transfer mechanism for application in energy

  14. Biliary excretion and distribution of 51Cr(III) and 51Cr(VI) in rats

    International Nuclear Information System (INIS)

    Cikrt, M.; Bencko, V.

    1979-01-01

    The biliary excretion and distribution of 51 Cr after intravenous administration of 51 Cr(III) ( 51 CrCl 3 ) or 51 Cr(VI) (Na 2 51 CrO 4 .4H 2 O) were studied in rats. The cumulative biliary excretion of 51 Cr 24 hrs after the injection was significantly higher after administration of 51 Cr(VI) than of 51 Cr(III) (3.51+-0.7% and 0.51+-0.05% of administered dose, respectively). This difference was especially due to a higher rate of biliary excretion of 51 Cr in the first hours after 51 Cr(VI) administration. The excretion of 51 Cr via feces was also higher after administration of 51 Cr(VI) (7.35+-0.45%) of administered dose, as against 4.23+-0.23% after 51 Cr(III). On the other hand, no significant difference in urinary excretion of 51 Cr was found. Statistically significant differences were also observed in the distribution of 51 Cr in the organism after administration of both valence states of the metal. (author)

  15. Ti{sub 3}CrCu{sub 4}: A possible 2-D ferromagnetic spin fluctuating system

    Energy Technology Data Exchange (ETDEWEB)

    Dhar, S. K.; Kulkarni, R.; Goyal, Neeraj [Department of Condensed Matter Physics & Materials Science, T.I.F.R., Homi Bhabha Road, Colaba, Mumbai, 400005 (India); Provino, A.; Manfrinetti, P. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Paudyal, D. [The Ames Laboratory, US Department of Energy, Iowa State University, Ames, IA 50011-3020 (United States)

    2016-05-15

    Ti{sub 3}CrCu{sub 4} is a new ternary compound which crystallizes in the tetragonal Ti{sub 3}Pd{sub 5} structure type. The Cr atoms form square nets in the a-b plane (a = 3.124 Å) which are separated by an unusually large distance c = 11.228 Å along the tetragonal axis, thus forming a -2-D Cr-sublattice. The paramagnetic susceptibility is characterized by a low effective moment, μ{sub eff} = 1.1 μ{sub B}, a low paramagnetic Curie temperature θ{sub P} (below 7 K) and a temperature independent χ{sub 0} = 6.7 x 10{sup −4} emu/mol. The magnetization at 1.8 K increases rapidly with field nearly saturating to 0.2 μ{sub B}/f.u. The zero field heat capacity C/T shows an upturn below 7 K (∼190 mJ/mol K{sup 2} at ∼0.1K) which is suppressed in applied magnetic fields and interpreted as suggesting the presence of spin fluctuations. The resistivity at low temperatures shows non-Fermi liquid behavior. Overall, the experimental data thus reveal an unusual magnetic state in Ti{sub 3}CrCu{sub 4}, which likely has its origin in the layered nature of the Cr sub-lattice and ferromagnetic spin fluctuations. Density functional theoretical calculations reveal a sharp Cr density of states peak just above the Fermi level, indicating the propensity of Ti{sub 3}CrCu{sub 4} to become magnetic.

  16. Ab initio/GIAO-CCSD(T) (13)C NMR study of the rearrangement and dynamic aspects of rapidly equilibrating tertiary carbocations, C6H13(+) and C7H15(+).

    Science.gov (United States)

    Olah, George A; Prakash, G K Surya; Rasul, Golam

    2016-01-05

    The rearrangement pathways of the equilibrating tertiary carbocations, 2,3-dimethyl-2-butyl cation (C6H13(+), 1), 2,3,3-trimethyl-2-butyl cation (C7H15(+), 5) and 2,3-dimethyl-2-pentyl cation (C7H15(+), 8 and 9) were investigated using the ab initio/GIAO-CCSD(T) (13)C NMR method. Comparing the calculated and experimental (13)C NMR chemical shifts of a series of carbocations indicates that excellent prediction of δ(13)C could be achieved through scaling. In the case of symmetrical equilibrating cations (1 and 5) the Wagner-Meerwein 1,2-hydride and 1,2-methide shifts, respectively, produce the same structure. This indicates that the overall (13)C NMR chemical shifts are conserved and independent of temperature. However, in the case of unsymmetrical equilibrating cations (8 and 9) the Wagner-Meerwein shift produces different tertiary structures, which have slightly different thermodynamic stabilities and, thus, different spectra. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level structure 8 is only 90 calories/mol more stable than structure 9. Based on computed (13)C NMR chemical shift calculations, mole fractions of these isomers were determined by assuming the observed chemical shifts are due to the weighted average of the chemical shifts of the static ions. © 2015 Wiley Periodicals, Inc.

  17. Anisotropic magnetic properties of Dy{sub 6}Cr{sub 4}Al{sub 43} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Arvind, E-mail: arvindmaurya@tifr.res.in; Thamizhavel, A., E-mail: arvindmaurya@tifr.res.in; Dhar, S. K., E-mail: arvindmaurya@tifr.res.in [Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Mumbai-400005 (India)

    2014-04-24

    We have studied the anisotropic magnetic behavior of the rare earth intermetallic compound Dy{sub 6}Cr{sub 4}Al{sub 43}. This compound crystallizes in the hexagonal symmetry and orders ferromagnetically at 8.3 K as confirmed by the magnetic susceptibility and heat capacity measurements. A significant anisotropy in the magnetization is observed between the c axis and the ab-plane. The easy axis liesin theab-plane at low temperatures; however it orients itselfalong the c-axis above 170 K as inferred from the susceptibility data.

  18. Grain boundary migration induced segregation in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

    1996-10-01

    Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

  19. The effects of some factors on the creep behavior of type 304 stainless steel

    International Nuclear Information System (INIS)

    Nakazawa, Takanori; Abo, Hideo

    1978-01-01

    The effects of some factors on the creep behavior of Type 304 stainless steel have been studied and the relations between the strength and the structure of the steel have been discussed. The main results obtained are as follows. (1) The creep and creep rupture strengths at 550 0 , 600 0 and 650 0 C increased with the increase in cold working rate up to 20%, but the creep rupture elongation decreased. These facts could be explained by the strengthening of matrix by dislocations which acted as precipitation sites of carbides during creep. (2) The steel was aged for up to 3000 hr at 550 0 to 700 0 C. Carbides precipitated on the grain boundaries and in the neighborhood of the grain boundaries. With long-time or high-temperature aging, the creep strength and creep rupture strength decreased, but the creep rupture elongation increased. (3) The creep strength at 600 0 C was independent of the grain size. Crack initiation was accelerated by the growth of grains, and therefore the creep rupture strength and elongation were decreased. (4) The creep strength of Type 304 stainless steel was increased by uniformly distributed fine carbides (Cr, Fe) 23 C 6 which precipitated on dislocations during creep. (author)

  20. The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau

    Science.gov (United States)

    Khaliullina, A. I.

    2018-04-01

    A detailed study of the orbital-period variations of the Algol-type eclipsing binaries with earlyspectral- type primary components U CrB and RW Tau has been performed. The period variations in both systems can be described as a superposition of secular and cyclic variations of the period. A secular period increase at a rate of 2.58d × 10-7/year is observed for U CrB, which can be explained if there is a uniform flow of matter from the lower-mass to the higher-mass component, with the total angular momentum conserved. RW Tau features a secular period decrease at a rate of -8.6d × 10-7/year; this could be due to a loss of angular momentum by the binary due to magnetic braking. The cyclic orbital-period variations of U CrB and RWTau can be explained by the motion of the eclipsing binary systems along their long-period orbits. In U CrB, this implies that the eclipsing binary moves with a period of 91.3 years around a third body with mass M 3 > 1.13 M ⊙; in RW Tau, the period of the motion around the third body is 66.6 years, and the mass of the third body is M 3 > 1.24 M ⊙. It also cannot be ruled out that the variations are due to the magnetic cycles of the late-type secondaries. The residual period variations could be a superposition of variations due to non-stationary ejection of matter and effects due to magnetic cycles.

  1. Natural Cr3+-rich ettringite: occurrence, properties, and crystal structure

    Science.gov (United States)

    Seryotkin, Yurii V.; Sokol, Ella V.; Kokh, Svetlana N.; Murashko, Mikhail N.

    2017-08-01

    Cr3+-rich ettringite with Cr3+→Al substitution and Cr/(Cr + Al) ratios up to 0.40-0.50 was found in mineral assemblages of the Ma'aleh Adumim area of Mottled Zone (Judean Desert). The Cr3+-rich compositions were the latest in the thaumasite → ettringite-thaumasite solid solution → ettringite → ettringite-bentorite solid solution series. The mineral-forming solution was enriched in Cr3+ and had a pH buffered by afwillite at 11-12. Chromium was inherited from larnite rocks produced by high-temperature combustion metamorphic alteration of bioproductive calcareous sediments. The Cr/(Cr + Al) ratios are within 0.10-0.15 in most of the analysed crystals. This degree of substitution imparts pink colouration to the crystals, but does not affect their habit (a combination of monohedra and a prism). The habit changes to pyramid faces in coarse and later Cr3+-bearing crystals as Cr/(Cr + Al) ratios increase abruptly to 0.40-0.50. Single-crystal XRD analysis of one Cr-free and two Cr3+-rich samples and their structure determination and refinement indicate that the Cr-rich crystals (with Cr/(Cr + Al) to 0.3) preserve the symmetry and metrics of ettringite. The Ca-O bonding network undergoes differentiation with increase of Cr3+ concentration at octahedral M sites. The compression of Ca2 and expansion of Ca1 polyhedra sub-networks correlates with the degree of Cr3+→Al substitution.

  2. 14 CFR 23.307 - Proof of structure.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Proof of structure. 23.307 Section 23.307... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure General § 23.307 Proof of structure. (a) Compliance with the strength and deformation requirements of § 23.305 must be shown for each...

  3. DFT study on the crystal, electronic and magnetic structures of tantalum based double perovskite oxides Ba2MTaO6 (M = Cr, Mn, Fe) via GGA and GGA + U

    Science.gov (United States)

    Saad, H.-E.; Musa, M.; Elhag, Ahmed

    2018-06-01

    In this paper, we study the crystal, electronic and magnetic structures of three tantalum based double perovskite oxides Ba2MTaO6 (M = Cr, Mn, Fe). All calculations were performed using the full-potential linear augmented plane-wave (PF-LAPW) method based on the first-principles density functional theory (DFT). For the exchange correlation potential, the generalized gradient approximation (GGA) and GGA plus on-site Coulomb parameter (GGA + U) were employed. The structural optimization reveals that the three compounds are stable in cubic structure (space group Fm-3m; tilt system a0a0a0). The band structure, density of states (DOS), charge density and spin magnetic moments were calculated and analyzed in details. By analysis the band structure and DOS, Ba2MTaO6 exhibits an insulating behavior (M = Cr, Fe) and a half-metallic (HM) nature (M = Mn). GGA + U method yields quite accurate results for the band-gap (Eg) as compared with GGA. We found that all three compounds have stable ferromagnetic (FM) ground state within GGA and GGA + U calculations. The M3+ (3d) ions contribute the majority in the total spin magnetic-moments, while, the empty T5+ (5d) ions carry very small induced magnetic moment via the M (3d)-O (2p)-Ta (5d) hybridization.

  4. Fragrance material review on 2-(3-methylphenyl) ethanol.

    Science.gov (United States)

    Scognamiglio, J; Jones, L; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of 2-(3-methylphenyl) ethanol when used as a fragrance ingredient is presented. 2-(3-Methylphenyl) ethanol is a member of the fragrance structural group Aryl Alkyl Alcohols and is a primary alcohol. The AAAs are a structurally diverse class of fragrance ingredients that includes primary, secondary, and tertiary alkyl alcohols covalently bonded to an aryl (Ar) group, which may be either a substituted or unsubstituted benzene ring. The common structural element for the AAA fragrance ingredients is an alcohol group -C-(R1)(R2)OH and generically the AAA fragrances can be represented as an Ar-C-(R1)(R2)OH or Ar-Alkyl-C-(R1)(R2)OH group. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. A safety assessment of the entire Aryl Alkyl Alcohols will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all other branched chain saturated alcohols in fragrances. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Neutron powder diffraction investigation of magnetic structure and spin reorientation transition of HoFe{sub 1-x}Cr{sub x}O{sub 3} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinzhi [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Hao, Lijie, E-mail: haolijie@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Liu, Yuntao; Ma, Xiaobai; Meng, Siqin; Li, Yuqing; Gao, Jianbo; Guo, Hao; Han, Wenze; Sun, Kai; Wu, Meimei [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Chen, Xiping; Xie, Lei [Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Klose, Frank [Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China)

    2016-11-01

    Orthoferrite solid solution HoFe{sub 1−x}Cr{sub x}O{sub 3} (x=0, 0.2,…,1.0) was synthesized via solid state reaction methods. The crystal structure, magnetism and spin reorientation properties of this system were investigated by X-ray diffraction, neutron powder diffraction and magnetic measurements. For compositions of x≤0.6, the system exhibits similar magnetic properties to HoFeO{sub 3}. With increasing Cr-doping, the system adopts a Γ{sub 4}(G{sub x}A{sub y}F{sub z}) magnetic configuration with a decreased Neel temperature from 640 K to 360 K. A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was also observed in this system with an increase in transition temperature from 56 K to about 200 K due to competition between the Fe(Cr)–Fe(Cr) and Ho–Fe(Cr) interactions. For the x≥0.8, the system behaves more like HoCrO{sub 3} which adopts a Γ{sub 2}(F{sub x}C{sub y}G{sub z}) configuration with no spin reorientation below the Neel temperature T{sub N}. Throughout the whole substitution range, we found that the saturated moment of Fe(Cr) was less than the ideal value for a free ion, which implies the existence of spin fluctuation in this system. A systematic magnetic structure variation with Cr-substitution is revealed by Rietveld refinement. A phase diagram combining the results of the magnetic measurements and neutron powder diffraction results was obtained. - Highlights: • With Cr-substitution in the HoFe{sub 1−x}Cr{sub x}O{sub 3} system, A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was observed with an increase in transition temperature from 56 K to about 200 K for x=0−0.6. • The saturated moment of Fe(Cr) position was found to be systematically less than the ideal value of free ion, and thus implies the presence of spin quantum fluctuation. • A composition–temperature phase diagram throughout x=0–1 for HoFe{sub 1−x}Cr{sub x}O{sub 3} system was established.

  6. On new ternary equiatomic scandium transition metal aluminum compounds ScTAl with T = Cr, Ru, Ag, Re, Pt, and Au

    Energy Technology Data Exchange (ETDEWEB)

    Radzieowski, Mathis; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Haverkamp, Sandra [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; University of Sao Paulo, Sao Carlos, SP (Brazil). Inst. of Physics

    2016-08-01

    The new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn{sub 2} type, P6{sub 3}/mmc, a = 525.77(3), c = 858.68(5) pm, R{sub 1} = 0.0188, wR{sub 2} = 0.0485, 204 F{sup 2} values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R{sub 1} = 0.0326, wR{sub 2} = 0.0458, 448 F{sup 2} values, 20 variables and ScAuAl, HfRhSn type, P anti 62c, a = 722.88(4), c = 724.15(4) pm, R{sub 1} = 0.0316, wR{sub 2} = 0.0653, 512 F{sup 2} values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by {sup 27}Al and {sup 45}Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

  7. Clonal structure of Trypanosoma cruzi Colombian strain (biodeme Type III: biological, isoenzymic and histopathological analysis of seven isolated clones

    Directory of Open Access Journals (Sweden)

    Camandaroba Edson Luiz Paes

    2001-01-01

    Full Text Available The clonal structure of the Colombian strain of Trypanosoma cruzi, biodeme Type III and zymodeme 1, was analyzed in order to characterize its populations and to establish its homogeneity or heterogeneity. Seven isolated clones presented the basic characteristics of Biodeme Type III, with the same patterns of parasitemic curves, tissue tropism to skeletal muscle and myocardium, high pathogenicity with extensive necrotic-inflammatory lesions from the 20th to 30th day of infection. The parental strain and its clones C1, C3, C4 and C6, determined the higher levels of parasitemia, 20 to 30 days of infection, with high mortality rate up to 30 days (79 to 100%; clones C2, C5 and C7 presented lower levels of parasitemia, with low mortality rates (7.6 to 23%. Isoenzymic patterns, characteristic of zymodeme 1, (Z1 were similar for the parental strain and its seven clones. Results point to a phenotypic homogeneity of the clones isolated from the Colombian strain and suggest the predominance of a principal clone, responsible for the biological behavior of the parental strain and clones.

  8. Comparison of mechanical behavior of TiN, TiNC, CrN/TiNC, TiN/TiNC films on 9Cr18 steel by PVD

    Science.gov (United States)

    Feng, Xingguo; Zhang, Yanshuai; Hu, Hanjun; Zheng, Yugang; Zhang, Kaifeng; Zhou, Hui

    2017-11-01

    TiN, TiNC, CrN/TiNC and TiN/TiNC films were deposited on 9Cr18 steel using magnetron sputtering technique. The morphology, composition, chemical state and crystalline structure of the films were observed and analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Hardness and adhesion force were tested by nanoindentation and scratch tester, respectively. The friction and wear behavior of TiN, TiNC, CrN/TiNC and TiN/TiNC films sliding against GCr15 balls were investigated and compared synthetically using ball-on-disk tribometer. It was found that Tisbnd N, Tisbnd C, Tisbnd Nsbnd C and Csbnd C bonds were formed. The TiN/TiNC film was composed of TiN, TiC and TiNC phases. Hardness and adhesion force results indicated that although the TiN film possessed the highest hardness, its adhesion force was lowest among all the films. Tribological test results showed that the friction coefficient of TiN/TiNC was much lower than that of TiN and the wear rate decreases remarkably from 2.3 × 10-15 m3/Nm to 7.1 × 10-16 m3/Nm, which indicated the TiN/TiNC film has better wear resistance.

  9. Ethylene polymerization by PN3-type pincer chromium(III) complexes

    KAUST Repository

    Gong, Dirong; Liu, Wen; Chen, Tao; Chen, Zhongren; Huang, Kuo-Wei

    2014-01-01

    Chromium (III) complexes, Cr1, [2,6-(tBu2PNH) 2C5H4N]CrCl3; Cr2, [2,6-(Ph 2PNH)2C5H4N]CrCl3; Cr3, [2-(tBu2PNH)C5H4N]CrCl3 THF; Cr4, [6-(tBu2PNH)C5H4N-2- CH2NEt2]CrCl3; Cr5, [6-(tBu 2PNH)C5H4N-2-C3H2N 2]CrCl3; Cr6, [6-(tBu2PNH)C 5H4N-2-(3,5-Me2)C3H 2

  10. Phase transitions of doped carbon in CrCN coatings with modified mechanical and tribological properties via filtered cathodic vacuum arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Guan, J.J. [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Wang, H.Q. [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Qin, L.Z., E-mail: qin8394@163.com [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Liao, B.; Liang, H. [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Li, B. [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China)

    2017-04-15

    The CrCN coatings were fabricated onto Si (1 1 1) wafers and SUS304 stainless steel plates using filtered cathodic vacuum arc deposition (FCVAD) technique under different flow ratios of N{sub 2}/C{sub 2}H{sub 2} gas mixture. The morphology, crystalline structure and chemical composition of the coatings were characterized. It was found that the grain size reduce with increasing carbon content, which makes the CrCN coatings refined and smooth. The quasi-one-dimensional carbolite phase was also found in CrN host lattice with C{sub 2}H{sub 2} content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CN{sub x} phases as C{sub 2}H{sub 2} content exceeds 20%. Moreover, we examined the mechanical and tribological properties of the CrCN coatings, and the experimental results confirmed that the friction coefficient of the coatings descend to the lowest value as 0.39 with 30% C{sub 2}H{sub 2} content, due to the graphite (sp{sup 2} C−C) phase embed in CrN host lattice; while the chromium carbon (Cr{sub 3}C{sub 2}) and diamond (sp{sup 3} C−C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C{sub 2}H{sub 2} content.

  11. Crystallography of sigma phase precipitation in superaustenitic Fe-22Cr-21Ni-6Mo-0.3N stainless steels

    International Nuclear Information System (INIS)

    Lee, Tae Ho; Jung, Yun Chul; Kim, Sung Joon

    1999-01-01

    The crystallographic features of sigma phase precipitation in super austenitic Fe-22Cr-21Ni-6Mo-(0.3N) stainless steels during isothermal aging were investigated utilizing transmission electron microscopy. The sigma phase precipitated along the austenite grain boundaries even after solution treatment due to higher Mo contents and remained stable throughout aging at 900 .deg. C up to 168 hours. The sigma phase observed in this study was found to be ternary Fe-Cr-Mo sigma phase and had tetragonal structure with lattice parameters of a=9.17A and c=4.74A. The orientation relationships between the sigma phase and austenite were determined from the analyses of selected area diffraction patterns taken by various zone axes and stereo graphic analyses. The orientation relationships between sigma and austenite phases obtained in this study were as follows; 1) (110) γ ll (110) σ , [111] γ ll [001] σ and (112) γ ll (110) σ , [111] γ ll [001] σ and 2) (110) γ ll (110) σ , [112] γ ll [113] σ and (111) γ ll (332) σ , [112] γ ll [113] σ . However, the former orientation relationship was predominant throughout aging and the latter orientation relationship was scarcely observed in very limited aging condition

  12. Structure analysis of cation selective Cr-goethite as protective rust of weathering steel

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    We have performed extended X-ray absorption fine structure (EXAFS) analysis for artificial Cr-goethite to elucidate the local structure around Cr in Cr-goethite. The spectra were obtained using synchrotron radiation X-rays at the Photon Factory in Tsukuba. The first shell contributions were isolated by Fourier filtering EXAFS data, and the inverse Fourier transformed single-shell data were analyzed using a curve fitting method. The results show that Cr is coordinated with (7±1)O 2- ions. The protective characteristics of the Cr-goethite protective rust layer on weathering steel can be interpreted in terms of the O 2- coordination around Cr 3+ resulting in the creation of negative fixed charge in the Cr-goethite particles. (author)

  13. Crystal and Molecular Structure Studies of Ethyl 4-(4-Hydroxyphenyl-6-(6-methoxy-2-naphthyl-2-oxocyclohex-3-ene-1-carboxylate and Ethyl 4-(3-Bromophenyl-6-(6-methoxy-2-naphthyl-2-oxocyclohex-3-ene-1-carboxylate

    Directory of Open Access Journals (Sweden)

    Badiadka Narayana

    2012-08-01

    Full Text Available The crystal and molecular structures of the title compounds, ethyl 4-(4-hydroxyphenyl-6-(6-methoxy-2-naphthyl-2-oxocyclohex-3-ene-1-carboxylate (I and ethyl 4-(3-bromophenyl-6-(6-methoxy-2-naphthyl-2-oxocyclohex-3-ene-1-carboxylate (II, are reported and confirmed by single crystal X-ray diffraction data. Compound (I, C26H24O5, crystallizes from a methanol solution in the monoclinic C2/c space group with eight molecules in the unit cell. The unit cell parameters are: a = 25.4114(5 Å, b = 8.47440(10 Å, c = 20.6921(4 Å, β = 108.328(2° and V = 4229.92(13 Å3. Disorder is observed throughout the entire molecule with an occupancy ratio 0.690(2:0.310(2. Compound (II, C26H23O4Br, crystallizes from an ethyl acetate solution in the monoclinic P21/c spacegroup with four molecules in the unit cell. The unit cell parameters are a = 17.8991(9 Å, b = 11.4369(6 Å, c = 10.8507(5 Å, β = 92.428(4° and V = 2219.25(19 Å3. Disorder is observed in the cyclohexenone ring and the carboxylate group with an occupancy ratio 0.830(6:0.170(6. Weak O–H...O (I or C–H...O (II intermolecular interactions are observed which influence crystal packing stability. These chalcone derivative types of molecules are important in their ability to act as activated unsaturated systems in conjugated addition reactions of carbanions in the presence of basic catalysts which exhibit a multitude of biological activities.

  14. Expeditious Entry to Novel 2-Methylene-2,3-dihydrofuro[3,2-c] chromen-2-ones from 6-Chloro-4-hydroxychromen-2-one and Propargylic Alcohols

    Directory of Open Access Journals (Sweden)

    Josefina Díez

    2011-08-01

    Full Text Available A catalytic system consisting of the ruthenium(II complex [Ru(η3-2-C3H4Me(CO(dppf][SbF6] (dppf = 1,1’-bis(diphenylphosphinoferrocene and trifluoroacetic acid has been used to promote the coupling of secondary propargylic alcohols with 6-chloro-4-hydroxychromen-2-one. The reactions afforded unusual 2-methylene-2,3-dihydrofuro[3,2-c]chromen-2-ones in good yields.

  15. Cr3+ and Cr4+ luminescence in glass ceramic silica

    International Nuclear Information System (INIS)

    Martines, Marco A.U.; Davolos, Marian R.; Jafelicci, Miguel Junior; Souza, Dione F. de; Nunes, Luiz A.O.

    2008-01-01

    This paper reports on the effect of glass ceramic silica matrix on [CrO 4 ] 4- and Cr 2 O 3 NIR and visible luminescence. Chromium-containing silica was obtained by precipitation from water-glass and chromium nitrate acid solution with thermal treatment at 1000 deg. C. From XRD results silica and silica-chromium samples are crystalline. The chromium emission spectrum presents two main broad bands: one in the NIR region (1.1-1.7μm) and other in the visible region (0.6-0.7μm) assigned to Cr 4+ and to Cr 3+ , respectively. This thermal treated glass ceramic silica-chromium sample stabilizes the [CrO 4 ] 4- where Cr 4+ substitutes for Si 4+ and also hexacoordinated Cr 3+ group probably as segregated phase in the system. It can be pointed out that luminescence spectroscopy is a powerful tool for detecting the two chromium optical centers in the glass ceramic silica

  16. On the abrasion of heat-treated 2.8C21Cr1Mo white cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rubaie, Kassim S.; Preti, Orlando [Centro Universitario SOCIESC, Joinville (Brazil). Engenharia Mecanica; Pohl, Michael [Bochum Univ. (Germany). Inst. fuer Werkstoffe

    2016-09-15

    The abrasion behaviour of heat-treated 2.8C21Cr1Mo cast iron was studied. The specimens were destabilised at two temperatures, 980 and 1050 C, for 4 h, air hardened, and then tempered at five temperatures, 220, 320, 400, 500, and 620 C, for 2 h followed by air cooling. Using a pin-on-plate abrasion apparatus, the specimens were abraded on four types of bonded abrasives (silicon carbide, corundum, flint, and glass). The effect of work hardening on the abrasion resistance was investigated. It was found that the increase in alloy hardness produced by heat treatment had little effect on the abrasion resistance against silicon carbide or corundum; the inverse was true against flint or glass. The as-hardened structure containing 40% retained austenite gave the best abrasion resistance, whereas the hardened and tempered at 620 C showed the worst. Both bulk hardness and matrix hardness before wear correlated poorly with the abrasion resistance. Therefore, a general model ''equivalent hardness'' was developed, in which the hardness of the abraded matrix was considered. With this model, the abrasion behaviour can be clearly analysed.

  17. Synthesis and structural characterization of luminescent inorganic materials of the type CS2NaErBr6 and CS2NaHoBr6

    International Nuclear Information System (INIS)

    Poblete, V.H.; Fack, G.

    2001-01-01

    The synthesis and structural characterization is described of two luminescent materials, with technological [1] and spectroscopic [2] interest, whose crystallographic charts have not been published in the literature. The synthesis of both systems: Cs 2 NaErBr 6 and CS 2 NaHoBr 6 , was done using solid state reactions in a controlled environment. The thermal analyses DTA/TGA, applied with a temperature gradient of 10 o C/min., established crystallization ranges of 490,4 o C to 545,4 o C, for the elpasolite CS 2 NaHoBr 6 and 501 o C to 556 o C, for the structure CS 2 NaErBr 6 .. The heat vacuum treatments were carried out at 505 o C and 526 o C respectively, obtaining optimum crystallization. The structural characterization was performed with powdered X-ray diffraction (XRD). The range between 12 o and 80 o (2θ), was analyzed for 3352 points, measured steps of 0.02 o (2θ using the Rietveld profile refining program. The following crystallographic parameters were established: a 0 = 11,279(1), and 11,293(4) Angstroms, for the two structures analyzed, respectively. The relationship R exp wp in both cases is highly accurate for the 32 test lines that were analyzed. The structures present cubic closed packing Cs 1+ 3 Cl 1- , with Ho 3+ and Er 3+ atoms, filling the octahedral holes. The test data obtained will be very useful for completing the mass of experimental data needed to develop the design engineering, with specific applications for luminescent devices

  18. Anti-wetting Cu/Cr coating with micro-posts array structure fabricated by electrochemical approaches

    International Nuclear Information System (INIS)

    Zhou, Yufeng; Hang, Tao; Li, Feng; Li, Ming

    2013-01-01

    Microposts structured Cu/Cr multilayer coating was prepared by a simple two-step approach combining electroless and electro deposition. Surface morphologies of the as-prepared Cu/Cr multilayer coating characterized by field emission scanning electron microscopy show that this multilayer coating exhibits micro-posts arrayed structure with a layer of Cr uniformly covering the circular conical surface of Cu micro-cones array. The wettability test shows that the contact angle of Cu/Cr multilayer surface with water drop can be greater than 140° by optimizing the electrodeposition time of Cr. The mechanism of hydrophobicity of both the micro-cones arrayed and micro-posts arrayed structures was briefly discussed by comparing two different wetting modes. Due to its good anti-wetting property and unique structure, the micro-posts arrayed Cu/Cr multilayer coating is expected for extensive practical applications.

  19. A first principle study of phase stability, electronic structure and magnetic properties for Co{sub 2−x}Cr{sub x}MnAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rached, H. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Rached, D., E-mail: rachdj@yahoo.fr [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique de la Matière, (LPQ3M), Université de Mascara, Mascara 29000 (Algeria); Abidri, B.; Rabah, M.; Benkhettou, N. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Omran, S. Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-04-01

    The structural stabilities, electronic and magnetic properties of Co{sub 2−x}Cr{sub x}MnAl alloys with (x=0,1 and 2) were investigated using the full-potential linear muffin-tin orbital (FP-LMTO) method, in the framework of the density functional theory (DFT) within the generalized gradient approximation (GGA) for the exchange correlation functional. The ground state properties including lattice parameter, bulk modulus for the two considered crystal structures Hg{sub 2}CuTi-Type (X-Type) and Cu{sub 2}MnAl-Type (L2{sub 1}-Type) are calculated. The half-metallicity within ferromagnetic ground state starts to appear in CoCrMnAl and Cr2MnAl. In the objective for the proposition of the new HM-FM in the Full-Heusler alloys, our results classified CoCrMnAl as new HM-FM material with high spin polarization. - Highlights: • Based on DFT calculations, Co2-xCrxMnAl Heusler alloys have been investigated. • The magnetic phase stability was determined from the total energy calculations. • The LMTO calculations have classified CoCrMnAl as new HM-FM material with high spin polarization.

  20. Microstructural, structural and optical properties of nanoparticles of PbO-CrO3 pigment synthesized by a soft route

    Directory of Open Access Journals (Sweden)

    V. D. Araújo

    2015-03-01

    Full Text Available PbCrO4 and Pb2CrO5 particles were synthesized by the polymeric precursor method. Structural and microstructural properties of the particles were characterized by scanning electron microscopy with field emission gun, X-ray diffraction, and Raman spectroscopy techniques. The diffuse reflectance technique was employed to study the optical properties in the 400-700 nm range. The optical bandgap of the samples was obtained indirectly. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders as a function of the heat treatment (400-700 ºC. The powders displayed colors ranging from green to red. X-ray diffraction patterns showed the presence of monoclinic PbCrO4 phase in green samples, while red powders had a monoclinic Pb2CrO5 phase structure. The Raman spectra of the PbCrO4 and Pb2CrO5 powders were in good agreement with those reported in the literature. The synthesized compounds can be used as green and red pigments with high thermal stability.