WorldWideScience

Sample records for neutron diffraction applications

  1. Applications of TOF neutron diffraction in archaeometry

    Energy Technology Data Exchange (ETDEWEB)

    Kockelmann, W. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Siano, S.; Bartoli, L. [Istituto di Fisica Applicata - CNR, Sesto Fiorentino (Italy); Visser, D. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Netherlands Organisation for Scientific Research (NWO), Den Haag (Netherlands); Hallebeek, P. [Netherlands Institute for Cultural Heritage (ICN), Amsterdam (Netherlands); Traum, R. [Kunsthistorisches Museum Wien, Muenzkabinett, Vienna (Austria); Linke, R.; Schreiner, M. [Akademie der Bildenden Kuenste, Institut fuer Wissenschaften und Technologien in der Kunst, Vienna (Austria); Kirfel, A. [Universitaet Bonn, Mineralogisch-Petrologisches Institut, Bonn (Germany)

    2006-05-15

    Neutron radiation meets the demand for a versatile diagnostic probe for collecting information from the interior of large, undisturbed museum objects or archaeological findings. Neutrons penetrate through coatings and corrosion layers deep into centimetre-thick materials, a property that makes them ideal for non-destructive examination of objects for which sampling is impractical or unacceptable. A particular attraction of neutron techniques for archaeologists and conservation scientists is the prospect of locating hidden materials and structures inside objects. Time-of-flight (TOF) neutron diffraction allows for the examination of mineral and metal phase contents, crystal structures, grain orientations, and microstructures as well as micro- and macro strains. A promising application is texture analysis which may provide clues to the deformation history of the material, and hence to specific working processes. Here we report on instructive examples of TOF neutron diffraction, including phase analyses of medieval Dutch tin-lead spoons, texture analyses of bronze specimens as well as of 16th-century silver coins. (orig.)

  2. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  3. Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

    Science.gov (United States)

    Ikeda, Yoshimasa; Taketani, Atsushi; Takamura, Masato; Sunaga, Hideyuki; Kumagai, Masayoshi; Oba, Yojiro; Otake, Yoshie; Suzuki, Hiroshi

    2016-10-01

    A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 μs of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 μs, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access

  4. Workshop on industrial application of neutron diffraction. Stress measurement by neutron diffraction

    CERN Document Server

    Minakawa, N; Morii, Y; Oyama, Y

    2002-01-01

    This workshop was planned to make use of the neutron from the reactor and the pulse neutron source JSNS for the industrial world. Especially, this workshop focused on the stress measurement by the neutron diffraction and it was held on the Tokai JAERI from October 15 to 16, 2001. The participant total was 93 and 40 participated from the industrial world. The introduction of the residual stress development of measurement technique by the neutron diffraction method and a research of the measurement of the residual stress such as the nuclear reactor material, the ordinary structure material, the composite material, the quenching steel, the high strength material were presented and discussed in this workshop. Moreover, it was introduced for the industrial world that an internal stress measurement is important for development of new product or an improvement of a manufacturing process. The question from the industrial world about which can be measured the product form, the size, the measurement precision, the reso...

  5. Polarized neutron diffraction and its application to spin density studies

    Institute of Scientific and Technical Information of China (English)

    Brenda; A.; DOUGAN

    2009-01-01

    Spin density distributions in molecular compounds containing unpaired electrons have been studied by polarized neutron diffraction (PND). The spin density distributions provide a unique perspective of the magnetic properties of the compounds. The background and fundamentals of polarized neutron diffraction are summarized in this review,followed by examples of applications in inorganic and organic chemistry. Spin densities in several compounds that are obtained by polarized neutron diffraction are highlighted. Spin densities in single molecular magnet [Fe8O2(OH)12(tacn)6]8+ and cyano-bridged K2[Mn(H2O)2]3[Mo(CN)7]2·6H2O demonstrate how to obtain magnetic interaction in the complexes by PND. PND studies of Ru(acac)3,containing one single unpaired electron,show small spin densities in this complex. Finally the use of PND in studying nitronyl nitroxide radicals is given. Our goal in this review is to illustrate how PND functions and how it serves as a sensitive tool in directly probing spin density in molecules.

  6. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  7. High-pressure neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

  8. Neutron diffraction stress determination in W-laminates for structural divertor applications

    Directory of Open Access Journals (Sweden)

    R. Coppola

    2015-07-01

    Full Text Available Neutron diffraction measurements have been carried out to develop a non-destructive experimental tool for characterizing the crystallographic structure and the internal stress field in W foil laminates for structural divertor applications in future fusion reactors. The model sample selected for this study had been prepared by brazing, at 1085 °C, 13 W foils with 12 Cu foils. A complete strain distribution measurement through the brazed multilayered specimen and determination of the corresponding stresses has been obtained, assuming zero stress in the through-thickness direction. The average stress determined from the technique across the specimen (over both ‘phases’ of W and Cu is close to zero at −17 ± 32 MPa, in accordance with the expectations.

  9. Optimizing Crystal Volume for Neutron Diffraction Studies

    Science.gov (United States)

    Snell, E. H.

    2003-01-01

    For structural studies with neutron diffraction more intense neutron sources, improved sensitivity detector and larger volume crystals are all means by which the science is being advanced to enable studies on a wider range of samples. We have chosen a simplistic approach using a well understood crystallization method, with minimal amounts of sample and using design of experiment techniques to maximize the crystal volume all for minimum effort. Examples of the application are given.

  10. Status of the Neutron Imaging and Diffraction Instrument IMAT

    Science.gov (United States)

    Kockelmann, Winfried; Burca, Genoveva; Kelleher, Joe F.; Kabra, Saurabh; Zhang, Shu-Yan; Rhodes, Nigel J.; Schooneveld, Erik M.; Sykora, Jeff; Pooley, Daniel E.; Nightingale, Jim B.; Aliotta, Francesco; Ponterio, Rosa C.; Salvato, Gabriele; Tresoldi, Dario; Vasi, Cirino; McPhate, Jason B.; Tremsin, Anton S.

    A cold neutron imaging and diffraction instrument, IMAT, is currently being constructed at the ISIS second target station. IMAT will capitalize on time-of-flight transmission and diffraction techniques available at a pulsed neutron source. Analytical techniques will include neutron radiography, neutron tomography, energy-selective neutron imaging, and spatially resolved diffraction scans for residual strain and texture determination. Commissioning of the instrument will start in 2015, with time-resolving imaging detectors and two diffraction detector prototype modules. IMAT will be operated as a user facility for material science applications and will be open for developments of time-of-flight imaging methods.

  11. Procedure for Computing Residual Stresses from Neutron Diffraction Data and its Application to Multi-Pass Dissimilar Weld

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [ORNL; Feng, Zhili [ORNL; Crooker, Paul [Electric Power Research Institute (EPRI)

    2011-01-01

    Neutron diffraction is a powerful tool for non-destructive measurement of internal residual stresses of welded structures. The conventional approach for determination of residual stresses requires the knowledge of stress-free lattice spacing a priori. For multiple-pass dissimilar metal welds common to nuclear reactor pipeline systems, the stress-free lattice parameter is a complex function of position due to the chemistry inhomogeneity in the weld region and can be challenging to determine experimentally. This paper presents a new approach to calculate the residual stress field in dissimilar welds without the use of stress-free lattice parameter. The theoretical basis takes advantage of the fact that the normal component of welding residual stresses is typically small for thin plate or pipe welds. The applicability of the new approach is examined and justified in a multi-pass dissimilar metal weld consisting of a stainless steel plate and a nickel alloy filler metal. The level of uncertainties associated with this new approach is assessed. Neutron diffraction experiment is carried out to measure the lattice spacing at various locations in the dissimilar weld. A comb-shaped specimen, electro-discharge machined from a companion weld, is used to determine the stress-free lattice spacing. The calculated results from the new approach are consistent with those from the conventional approach. The new approach is found to be a practical method for determining the two in-plane residual stress components in thin plate or pipe dissimilar metal welds.

  12. DNA hydration studied by neutron fiber diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.

  13. Neutron forward diffraction by single crystal prisms

    Indian Academy of Sciences (India)

    Sohrab Abbas; Apoorva G Wagh; Markus Strobl; Wolfgang Treimer

    2008-11-01

    We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to the incidence angle. We have measured the variation of neutron deflection and transmission across a Bragg reflection, for several single crystal prisms. The results agree well with theory.

  14. Magnetic correlations in oxides: Neutron diffraction and neutron depolarization study

    Indian Academy of Sciences (India)

    S M Yusuf

    2008-10-01

    We have studied magnetic correlations in several oxide materials that belong to colossal magnetoresistive, naturally occurring layered oxide showing low-dimensional magnetic ordering, solid oxide fuel cell interconnect materials, and magnetic nanoparticles using neutron diffraction and neutron depolarization techniques. In this paper, an overview of some of these results is given.

  15. Neutron diffraction of cell membranes (myelin).

    Science.gov (United States)

    Parsons, D F; Akers, C K

    1969-09-05

    Small-angle neutron diffraction (wavelength 4.05 angstroms) of human and rabbit sciatic nerve has been carried out by means of the Brookhaven high flux beam reactor with an automated slit camera. Most of the free water of the nerves was substituted in order to minimize incoherent scatter of hydrogen atoms. The differences in amplitude and phase shifts between neutrons and x-rays resulted in a neutron diffraction pattern that was completely different from the x-ray pattern. The neutron pattern consisted of a single peak of about 89-angstrom spacing in the region examined (up to 6-angstrom spacing). The strong third, fourth, and fifth order reflections (about 60, 45, and 36 angstroms) seen in the x-ray pattern were suppressed. The neutron data indicated a strong scattering from one portion of the membrane.

  16. Measurement of neutron diffraction with compact neutron source RANS

    Science.gov (United States)

    Ikeda, Y.; Takamura, M.; Taketani, A.; Sunaga, H.; Otake, Y.; Suzuki, H.; Kumagai, M.; Oba, Y.; Hama, T.

    2016-11-01

    Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface (0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials.

  17. Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

    CERN Document Server

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

    2002-01-01

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

  18. Neutron diffraction study of austempered ductile iron

    Science.gov (United States)

    Choi, C. S.; Sharpe, W.; Barker, J.; Fields, R. J.

    1996-04-01

    Crystallographic properties of an austempered ductile iron (ADI) were studied by using neutron diffraction. A quantitative phase analysis based on Rietveld refinements revealed three component phases, α-Fe (ferrite), γ-Fe (austenite), and graphite precipitate, with weight fractions of 66.0, 31.5, and 2.5 pct, respectively. The ferrite phases of the samples were found to be tetragonal, 14/mmm, with a c/a ratio of about 0.993, which is very close to the body-centered cubic (bcc) structure. The austenite phase had C atoms occupying the octahedral site of the face-centered cubic (fcc) unit cell with about 8 pct occupancy ratio. A strong microstrain broadening was observed for the two Fe phases of the samples. The particle sizes of the acicular ferrite phase were studied by using small angle neutron scattering. The analysis suggested a mean rod diameter of 700 A. The scattering invariant predicts a ferrite volume fraction consistent with the powder diffraction analysis. A textbook case of nodular graphite segregation, with average diameters ranging from 10 to 20 μm, was observed by optical micrography.

  19. Three-port beam splitter for slow neutrons using holographic nanoparticle-polymer composite diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Klepp, J.; Fally, M. [Faculty of Physics, University of Vienna, 1090 Wien (Austria); Tomita, Y. [Department of Engineering Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182 (Japan); Pruner, C. [Department of Materials Science and Physics, University of Salzburg, 5020 Salzburg (Austria); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

    2012-10-08

    Diffraction of slow neutrons by nanoparticle-polymer composite gratings has been observed. By carefully choosing grating parameters such as grating thickness and spacing, a three-port beam splitter operation for slow neutrons - splitting the incident neutron intensity equally into the {+-}1st and the 0th diffraction orders - has been realized. As a possible application, a Zernike three-path interferometer is briefly discussed.

  20. Microstructure of Horseshoe Nails Using Neutron Diffraction

    Science.gov (United States)

    Goossens, D. J.; Studer, A. J.; Stachurski, Z. H.

    2010-04-01

    Neutron diffraction allows nondestructive testing of the bulk microstructure of mechanical components. The microstructures of horseshoe nails made through three different processes have been explored as a function of position along the nail. Despite all nails being made of similar plain low-carbon steel and being process annealed after manufacture, the microstructures are far from the same. Nails made from strip, using a cold forging stamping process, show narrower diffraction peaks indicating a narrower distribution of lattice parameters and also show diffraction peak intensity ratios closer to those expected for unstrained steel. Thus, the distribution of the orientation of grains in these nails is closer to that of undistorted steel compared to nails made through the other two processes considered—one a drawing from wire and the other a combination of rolling and cold forging. The blades of the drawn nails showed little preferred orientation but the converse was true in the heads. Differing patterns of preferred orientation suggest that the various manufacturing approaches result in substantially different mechanical advantages for the three types of nails, a result in accord with mechanical testing.

  1. Neutron diffraction analysis of Cr-Ni-Mo-Ti austenitic steel after cold plastic deformation and fast neutrons irradiation

    Science.gov (United States)

    Voronin, V. I.; Valiev, E. Z.; Berger, I. F.; Goschitskii, B. N.; Proskurnina, N. V.; Sagaradze, V. V.; Kataeva, N. F.

    2015-04-01

    A quantitative assessment is presented of the dislocation density and relative fractions of edge and screw dislocations in reactor-steel samples 16Cr-15Ni-3Mo-1Ti subjected to preliminary cold deformation by rolling and subsequent fast neutron irradiation using neutron diffraction analysis. The Williamson-Hall modified method was used for calculations. It is shown that the fast neutron irradiation leads to a decrease in the density of dislocations that appeared after samples deformation. The applicability of neutron diffraction analysis to the examination of dislocation structure of deformed and irradiated materials is shown.

  2. Pulsed Neutron Powder Diffraction for Materials Science

    Science.gov (United States)

    Kamiyama, T.

    2008-03-01

    The accelerator-based neutron diffraction began in the end of 60's at Tohoku University which was succeeded by the four spallation neutron facilities with proton accelerators at the High Energy Accelerator Research Organization (Japan), Argonne National Laboratory and Los Alamos Laboratory (USA), and Rutherford Appleton Laboratory (UK). Since then, the next generation source has been pursued for 20 years, and 1MW-class spallation neutron sources will be appeared in about three years at the three parts of the world: Japan, UK and USA. The joint proton accelerator project (J-PARC), a collaborative project between KEK and JAEA, is one of them. The aim of the talk is to describe about J-PARC and the neutron diffractometers being installed at the materials and life science facility of J-PARC. The materials and life science facility of J-PARC has 23 neutron beam ports and will start delivering the first neutron beam of 25 Hz from 2008 May. Until now, more than 20 proposals have been reviewed by the review committee, and accepted proposal groups have started to get fund. Those proposals include five polycrystalline diffractometers: a super high resolution powder diffractometer (SHRPD), a 0.2%-resolution powder diffractometer of Ibaraki prefecture (IPD), an engineering diffractometers (Takumi), a high intensity S(Q) diffractometer (VSD), and a high-pressure dedicated diffractometer. SHRPD, Takumi and IPD are being designed and constructed by the joint team of KEK, JAEA and Ibaraki University, whose member are originally from the KEK powder group. These three instruments are expected to start in 2008. VSD is a super high intensity diffractometer with the highest resolution of Δd/d = 0.3%. VSD can measure rapid time-dependent phenomena of crystalline materials as well as glass, liquid and amorphous materials. The pair distribution function will be routinely obtained by the Fourier transiformation of S(Q) data. Q range of VSD will be as wide as 0.01 Å-1industries based on

  3. Neutron diffraction of unidirectional fiber-composites

    Energy Technology Data Exchange (ETDEWEB)

    Ochiai, Shojiro; Hojo, Masaki; Iwasaki, Naoya; Sawada, Takehiro; Inoue, Takashi; Tanaka, Mototsugu; Okumura, Ikuo; Ono, Masayoshi [Kyoto Univ. (Japan)

    1997-06-01

    Nb-Ti/Cu and Nb{sub 3}Al/Cu superconductive fiber-composites were studied by a neutron diffraction method. The results obtained showed that the aggregate structures were formed in the direction of <100> and <111> for copper and <110> for Nb-Ti filament. Nb{sub 3}Al grew up to the radius direction and formed the side face (210). Residual strain and stress of Cu in Nb-Ti/Cu and Nb{sub 3}Al/Cu composite were measured by TOF and PSD method. The value before smoothing treatment was 96 MPa, but the value after smoothing treatment became 40 MPa, near estimated value. (S.Y.)

  4. Feasibility of neutron diffraction on solid 3He

    Science.gov (United States)

    Siemensmeyer, K.; Schuberth, E. A.; Adams, E. D.; Takano, Y.; Guckelsberger, K.

    2000-07-01

    We have investigated the feasibility of neutron diffraction from solid 3He. The experiment will be performed at the HMI, first aiming for the properties of the antiferromagnetic ordering in the BCC phase and the ferromagnetic order in the HCP phase. Signal and beam heating considerations are essential to account for the enormous neutron absorption cross section of 3He. The study shows that neutron diffraction and transmission experiments are possible, relying on the experience gained from the neutron diffraction experiments on Cu and Ag at nanokelvin temperatures. A pressure cell has been developed which complies with the conflicting demands arising from the neutron and ultralow temperature aspects of the experiment. This work is a first step in an extensive effort to characterize 3He by neutron diffraction.

  5. Engineering related neutron diffraction measurements probing strains, texture and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Bjorn [Los Alamos National Laboratory; Brown, Donald W [Los Alamos National Laboratory; Tome, Carlos N [Los Alamos National Laboratory; Balogh, Levente [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory

    2010-01-01

    Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg's Law. From the measured diffraction patterns information about internal, or residual, strain can be deduced from the peak positions, texture information can be extracted from the peak intensities, and finally the peak widths can provide information about the microstructure, e.g. dislocation densities and grain sizes. The strains are measured directly from changes in lattice parameters, however, in many cases it is non-trivial to determine macroscopic values of stress or strain from the measured data. The effects of intergranular strains must be considered, and combining the neutron diffraction measurements with polycrystal deformation modeling has proven invaluable in determining the overall stress and strain values of interest in designing and dimensioning engineering components. Furthelmore, the combined use of measurements and modeling has provided a tool for elucidating basic material properties, such as critical resolved shear stresses for the active deformation modes and their evolution as a function of applied deformation.

  6. A new bridge technique for neutron tomography and diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Burca, G., E-mail: G.Burca@open.ac.uk [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); James, J.A. [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); Kockelmann, W. [ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Fitzpatrick, M.E. [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); Zhang, S.Y. [ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Hovind, J. [Paul Scherrer Institute (PSI), CH-5232, Villigen (Switzerland); Langh, R. van [Delft University of Technology, Department of Materials Science, Faculty 3mE, Mekelweg 2, 2628 CD Delft (Netherlands); Rijksmuseum Amsterdam, P.O. Box 74888, 1070 DN Amsterdam (Netherlands)

    2011-09-21

    An attractive feature of neutron techniques is the ability to identify hidden materials and structures inside engineering components and objects of art and archaeology. Bearing this in mind we are investigating a new technique, 'Tomography Driven Diffraction' (TDD), that exploits tomography data to guide diffraction experiments on samples with complex structures and shapes. The technique can be used utilising combinations of individual tomography and diffraction instruments, such as NEUTRA (PSI, CH) and ENGIN-X (ISIS, UK), but is also suitable for new combined imaging and diffraction instruments such as the JEEP synchrotron engineering instrument (DIAMOND, UK) and the proposed IMAT neutron imaging and diffraction instrument (ISIS, UK).

  7. Neutron sources and applications

    Energy Technology Data Exchange (ETDEWEB)

    Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  8. Structure factor determination of amorphous materials by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cuello, Gabriel J [Institut Laue Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble Cedex 9 (France)], E-mail: cuello@ill.eu

    2008-06-18

    An introduction is given to structure factor determination by means of neutron diffraction. The method of isotopic substitution, which allows us to separate the partial correlation functions, is also presented. Suitable instruments, the experimental procedures, and corrections are described. Other less-conventional techniques such as isomorphic substitution and anomalous dispersion are also discussed. Finally, examples of the structure factor determination in chalcogenide, molecular, telluride and phosphate glasses are discussed in order to illustrate the usefulness of the neutron diffraction technique.

  9. Single crystal neutron diffraction study of triglycine sulphate revisited

    Indian Academy of Sciences (India)

    Rajul Ranjan Choudhury; R Chitra

    2008-11-01

    In order to get the exact hydrogen-bonding scheme in triglycine sulphate (TGS), which is an important hydrogen bonded ferroelectric, a single crystal neutron diffraction study was undertaken. The structure was refined to an -factor of [2] = 0.034. Earlier neutron structure of TGS was reported with a very limited data set and large standard deviations. The differences between the present and the earlier reported neutron structure of TGS are discussed.

  10. Weissenberg-type neutron diffraction camera and its application to the structural and magnetic phase transitions of KMnF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S. [Kyushu University, Department of Physics, Faculty of Science, Fukuoka (Japan); University of Tokyo, Neutron Scattering Laboratory, ISSP, Ibaraki (Japan); Yoshimura, M.; Hidaka, M. [Kyushu University, Department of Physics, Faculty of Science, Fukuoka (Japan); Yoshizawa, H. [University of Tokyo, Neutron Scattering Laboratory, ISSP, Ibaraki (Japan)

    2006-07-15

    A Weissenberg-type neutron diffraction camera (W-NDC) equipped with a neutron imaging-plate (NIP) has been developed. The W-NDC gives Weissenberg-type and rotational diffraction patterns at low-temperature (10 Kdiffracted from the aluminum containers and the specimen holder, a radial slit with several polymer sheets coated with {sup 6}LiF powder is continuously oscillated around the specimen during measurements. A test structural analysis for a single crystal NaCl suggests that the integrated intensities of reflections obtained from the Weissenberg-type diffraction patterns adequately satisfy a structural refinement by means of a least square method, though a fading effect of the photon energy stored in the NIP should be regarded during measurements. Structural and magnetic phase transitions in KMnF{sub 3} have been studied by using the W-NDC, to eliminate an inconsistency for temperature, and to enable an ordering of the phase transition as reported. (orig.)

  11. Investigation of Acrylic Acid at High Pressure using Neutron Diffraction

    DEFF Research Database (Denmark)

    Johnston, Blair F.; Marshall, William G.; Parsons, Simon

    2014-01-01

    This article details the exploration of perdeuterated acrylic acid at high pressure using neutron diffraction. The structural changes that occur in acrylic acid-d4 are followed via diffraction and rationalised using the Pixel method. Acrylic acid undergoes a reconstructive phase transition to a n...

  12. Automatic control unit for A neutron diffraction crystal spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

    1982-01-01

    An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer.

  13. Diffraction on disordered materials using 'neutron-like' photons

    DEFF Research Database (Denmark)

    Neuefeind, J.; Poulsen, H.F.

    1995-01-01

    In the past photon diffraction has been carried out mainly using the characteristic radiation from X-ray tubes in the energy range from about 8-20 keV. Comparison of these experiments with neutron diffraction results is difficult since in this energy range the photoelectric absorption is the pred......In the past photon diffraction has been carried out mainly using the characteristic radiation from X-ray tubes in the energy range from about 8-20 keV. Comparison of these experiments with neutron diffraction results is difficult since in this energy range the photoelectric absorption...... is the predominant process. The photoelectric absorption decreases with lambda(3), so increasing the energy to about 100 keV has a drastic effect on the absorption coefficient. Photons in the high energy rang can be obtained conveniently from modern synchrotron sources. High energy photon diffraction has additional...

  14. Scientific Advancements and Technological Developments of High P-T Neutron Diffraction at LANSCE, Los Alamos

    Science.gov (United States)

    Zhao, Y.; Daemen, L. L.; Zhang, J.

    2003-12-01

    In-situ high P-T neutron diffraction experiments provide unique opportunities to study the crystal structure, hydrogen bonding, magnetism, and thermal parameters of light elements (eg. H, Li, B) and heavy elements (eg. Ta, U, Pu,), that are virtually impossible to determine with x-ray diffraction techniques. For example, thermoelasticity and Debye-Waller factor as function of pressure and temperature can be derived using in-situ high P-T neutron diffraction techniques. These applications can also be extended to a much broader spectrum of scientific problems. For instance, puzzles in Earth science such as the carbon cycle and the role of hydrous minerals for water exchange between lithosphere and biosphere can be directly addressed. Moreover, by introducing in-situ shear, texture of metals and minerals accompanied with phase transitions at high P-T conditions can also be studied by high P-T neutron diffraction. We have successfully conducted high P-T neutron diffraction experiments at LANSCE and achieved simultaneous high pressures and temperatures of 10 GPa and 1500 K. With an average 3-6 hours of data collection, the diffraction data are of sufficiently high quality for the determination of structural parameters and thermal vibrations. We have studied hydrous mineral (MgOD), perovskite (K.15,Na.85)MgF3, clathrate hydrates (CH4-, CO2-, and H2-), metals (Mo, Al, Zr), and amorphous materials (carbon black, BMG). The aim of our research is to accurately map bond lengths, bond angles, neighboring atomic environments, and phase stability in P-T-X space. Studies based on high-pressure neutron diffraction are important for multi-disciplinary science and we welcome researchers from all fields to use this advanced technique. We have developed a 500-ton toroidal press, TAP-98, to conduct simultaneous high P-T neutron diffraction experiments inside of HIPPO (High-Pressure and Preferred-Orientation diffractometer). We have also developed a large gem-crystal anvil cell, ZAP-01

  15. Neutron Diffraction and Optics of a Noncentrosymmetric Crystal. New Feasibility of a Search for Neutron EDM

    OpenAIRE

    Fedorov, V. V.; Voronin, V. V.

    2005-01-01

    Recently strong electric fields (up to 10^9 V/cm) have been discovered, which affect the neutrons moving in noncentrosymmetric crystals. Such fields allow new polarization phenomena in neutron diffraction and optics and provide, for instance, a new feasibility of a search for the neutron electric dipole moment (EDM). A series of experiments was carried out in a few last years on study of the dynamical diffraction of polarized neutrons in thick (1-10 cm) quartz crystals, using the forward diff...

  16. Neutron Diffraction Studies of Nuclear Magnetic Ordering in Copper

    DEFF Research Database (Denmark)

    Jyrkkiö, T.A.; Huiku, M.T.; Siemensmeyer, K.;

    1989-01-01

    to depend strongly on the external magnetic field between zero and the critical fieldB c=0.25 mT, indicating the existence of at least two antiferromagnetic phases. The results are compared to previous measurements of the magnetic susceptibility. Theoretical calculations do not provide a full explanation......We have constructed a two-stage nuclear demagnetization cryostat for neutron diffraction studies of nuclear magnetism in copper. The cryostat is combined with a two-axis neutron spectrometer which can use both polarized and unpolarized neutrons. By demagnetizing highly polarized copper nuclear...

  17. Diffraction plane dependence of elastic constants in residual stress measurement by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Okido, Shinobu; Hayashi, Makoto [Hitachi Ltd., Tokyo (Japan); Morii, Yukio; Minakawa, Nobuaki; Tsuchiya, Yoshinori

    1997-06-01

    In a residual stress measurement by x-ray diffraction method and a neutron diffraction method, strictly speaking, the strain measurement of various diffracted surface was conducted and it is necessary to use its elastic modulus to convert from the strain to the stress. Then, in order to establish the residual stress measuring technique using neutron diffraction, it is an aim at first to make clear a diffraction surface dependency of elastic modulus for the stress conversion in various alloys. As a result of investigations the diffraction surface dependency of elastic module on SUS304 and STS410 steels by using RESA (Neutron diffractometer for residual stress analysis) installed at JRR-3M in Tokai Establishment of JAERI, following results are obtained. The elastic modulus of each diffraction surface considering till plastic region could be confirmed to be in a region of {+-}20% of that calculated by Kroner`s model and to be useful for that used on conversion to the stress. And, error of this elastic modulus was thought to cause the transition and defect formed at inner portion of the materials due to a plastic deformation. (G.K.)

  18. Neutron Diffraction Investigation of MnAs under High Pressure

    DEFF Research Database (Denmark)

    Andresen, A.F; Fjellvag, H; Lebech, Bente

    1984-01-01

    Powdered MnAs has been investigated by neutron diffraction in a pressure cryostat, at hydrostatic pressures up to 13 kbar and temperatures down to 4.2 K. It has been found that in the orthorhombic MnP type structure, which under pressure is retained at low temperature, a spiral magnetic structure...

  19. Neutron diffraction test on spin-dependent short range interaction

    CERN Document Server

    Voronin, V V

    2008-01-01

    In this short note we discuss the possibility to get the constraint on the parameters of short range pseudomagnetic interaction of free neutron with matter from the crystal-diffraction experiment. It is demonstrated that for range of $\\lambda<10^{-6}$m this constraint can be a few order better than in any other method.

  20. Investigation of Methacrylic Acid at High Pressure Using Neutron Diffraction

    DEFF Research Database (Denmark)

    Marshall, William G.; Urquhart, Andrew; Oswald, Iain D. H.

    2015-01-01

    This article shows that pressure can be a low-intensity route to the synthesis of polymethacrylic acid. The exploration of perdeuterated methacrylic acid at high pressure using neutron diffraction reveals that methacrylic acid exhibits two polymorphic phase transformations at relatively low press...

  1. Grazing incidence neutron diffraction from large scale 2D structures

    Energy Technology Data Exchange (ETDEWEB)

    Toperverg, B. P.; Felcher, G. P.; Metlushko, V. V.; Leiner, V.; Siebrecht, R.; Nikonov, O.

    2000-01-13

    The distorted wave Born approximation (DWBA) is applied to evaluate the diffraction pattern of neutrons (or X-rays) from a 2D array of dots deposited onto a dissimilar substrate. With the radiation impinging on the surface at a grazing incidence angle {alpha}, the intensities diffracted both in and out the plane of specular reflection are calculated as a function of the periodicity of the array, height and diameter of the dots. The results are presented in the form of diffracted intensity contours in a plane with coordinates {alpha} and {alpha}{prime}, the latter being the glancing angle of scattering. The optimization of the experimental conditions for polarized neutron experiments on submicron dots is discussed. The feasibility of such measurements is confirmed by a test experiment.

  2. Lipids, membrane proteins and natural membranes studied by neutron scattering and diffraction: A review

    Science.gov (United States)

    Zaccai, Giuseppe

    1986-02-01

    Diffraction first observed from myelin 50 years ago was correctly attributed to a fluid crystal of lipids, because similar patterns were observed from extracted lipid preparations. Following on more recent X-ray work which characterized a variety of lipid-water structures, neutron diffraction experiments have provided detailed descriptions of the molecular conformations in lipid bilayers. For a long time, however, the molecular structure of membrane proteins remained elusive and the development of detergents for the extraction of active membrane proteins, and the discovery of naturally crystalline purple membrane were important breakthroughs in this field. Structural parameters of membrane proteins solubilised in detergent have been measured by neutron scattering with contrast variation techniques. Purple membrane has been studied extensively by neutron diffraction. It is an excellent illustration of the use of deuterium labeling by different approaches to address specific questions of molecular structure. These studies are reviewed with a special emphasis on aspects which are applicable to membranes in general.

  3. Magnetization and neutron diffraction studies on FeCrP

    Indian Academy of Sciences (India)

    Sudhish Kumar; Anjali Krishnamurthy; Bipin K Srivastava; A Das; S K Paranjpe

    2004-08-01

    Crystal structure and magnetic behaviour of FeCrP have been investigated using magnetization and neutron diffraction measurements. FeCrP crystallizes in orthorhombic FeZrP type structure (nma space group, = 4) in which Cr atoms occupy the pyramidal site and Fe atoms occupy the tetrahedral site with total preference. Structural parameters including positional parameters have been refined. The refined values of positional parameters for Fe and Cr are quite different from those in FeZrP. The nature of magnetization{temperature curve is suggestive of antiferromagnetic nature with N = 280 (± 10) K. Preliminary analysis of neutron diffraction pattern at 13 K is indicative of a rather complicated magnetic structure.

  4. Neutron diffraction investigations of kesterites: cation order and disorder

    Energy Technology Data Exchange (ETDEWEB)

    Schorr, Susan [Free University Berlin, Institute of Geological Sciences (Germany); Tovar, Michael [Helmholtz Zentrum Berlin fuer Materialien und Energie (Germany); Levcenco, Sergej; Napetrov, Alexander; Arushanov, Ernest [Academy of Sciences of Moldova Republic, Institute of Applied Physics, Chisinau (Moldova)

    2010-07-01

    The quaternary chalcogenides Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} have newly attracted attention as possible absorber materials in thin film solar cells. They crystallize in the kesterite type (space group I anti 4) or stannite type structure (space group I anti 42m), which are described as an ordered distribution of the cations on different structural sites. Cation disorder may cause site defects and hence influences the electronic properties of the material. Thus the degree of cation order/disorder plays a crucial role and was therefor in the focus of the presented investigations. A differentiation between the isoelectronic cations Cu{sup +} and Zn{sup 2+} is not possible using X-ray diffraction due to their similar scattering power. But their neutron scattering lengths are different, thus neutron diffraction opens the possibility to determine the cation distribution in these compounds. A simultaneous Rietveld analysis of neutron and X-ray powder diffraction data revealed that in dependence on the thermal history of the samples cation disorder appears. The correlation trend between cation order/disorder and the sample growth method (solid state synthesis, Bridgman method) are discussed.

  5. Heterogeneous Catalysis under pressure - In-situ neutron diffraction under industrial conditions

    Science.gov (United States)

    Kandemir, Timur; Girgsdies, Frank; Kasatkin, Igor; Kunkes, Edward; Liss, Klaus-Dieter; Peterson, Vanessa K.; Schlögl, Robert; Behrens, Malte

    2012-02-01

    The present work describes the application of a tubular reactor that allows in-situ neutron diffraction on working catalysts at high pressures. The designed reactor enables the application to a sample of industrially-relevant reaction conditions, i.e., in a temperature range up to 330° C and 60 bar pressure, coupled with online gas-analysis. Application of the cell is demonstrated by ammonia synthesis over a commercial catalyst with diffraction data obtained from the high-resolution powder diffractometer, Echidna, at the Australian Nuclear Science and Technology Organisation, ANSTO.

  6. Heterogeneous Catalysis under pressure - In-situ neutron diffraction under industrial conditions

    OpenAIRE

    Kandemir, T.; F. Girgsdies; Kasatkin, I.; Kunkes, E.; Liss, K.; Peterson, V.; Schlögl, R.; M. Behrens

    2012-01-01

    The present work describes the application of a tubular reactor that allows in-situ neutron diffraction on working catalysts at high pressures. The designed reactor enables the application to a sample of industrially-relevant reaction conditions, i.e., in a temperature range up to 330° C and 60 bar pressure, coupled with online gas-analysis. Application of the cell is demonstrated by ammonia synthesis over a commercial catalyst with diffraction data obtained from the high-resolution powder di...

  7. Refractive and diffractive neutron optics with reduced chromatic aberration

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, S.O., E-mail: stefan.poulsen@northwestern.edu [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Poulsen, H.F. [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Bentley, P.M. [European Spallation Source ESS AB, Box 176, 221 00 Lund (Sweden)

    2014-12-11

    Thermal neutron beams are an indispensable tool in physics research. The spatial and the temporal resolution attainable in experiments are dependent on the flux and collimation of the neutron beam which remain relatively poor, even for modern neutron sources. These difficulties may be mitigated by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams.

  8. 角度分散法中子衍射应力测试技术的应用%Application of Stress Measurement Technique by Angle Dispersive Neutron Diffraction

    Institute of Scientific and Technical Information of China (English)

    奂永慧; 徐平光; 殷匠

    2012-01-01

    由于中子具有较高的穿透能力,利用中子衍射容易获得块状试样内部特定位置的三维点阵面间距,从而实现应变/应力分布的较准确评价。首先介绍了各种应力测试技术的研究现状以及角度分散法中子衍射应力测试技术的基本原理;然后结合冲压成型试样的强度评价、复层钢板拉伸变形后的残余应变评价以及负荷条件下钢筋混凝土中钢筋的应力分布等中子衍射典型试验研究,说明角度分散法中子衍射应力测试技术在国外已广泛应用于工程结构件与材料内部应力的定量研究;最后展望了角度分散法中子衍射应力测试技术在国内的研究前景。%Because of the high penetrability of neutron beam in general metallic materials,neutron diffraction may easily acquire the three-dimensional information of polycrystalline diffraction from a well-defined gauge volume in any internal position of a structural material specimen or a machine component and then precisely evaluate the strain/stress distribution.The essential theory of angle dispersive neutron diffraction stress measurement technique based on a nuclear reactor was introduced,followed with several typical research examples including the work hardening evaluation of a cold press formed automobile component,the residual stain evaluation of a multilayered steel plate after uniaxial tensile deformation and the stress distribution of steel bar in a steel bar enforced concrete structural component under loading,showing that the angle dispersive neutron diffraction technique has been widely applied to the quantitative evaluations on internal stresses of engineering components and advanced materials in the developed countries.The rapid development and broad application of this strain/stress measurement technique have been highly expected in china.

  9. 3DXRD microscopy - a comparison with neutron diffraction

    CERN Document Server

    Poulsen, H F

    2002-01-01

    3DXRD microscopy is a novel tool for fast and non-destructive characterisation of the individual grains and sub-grains inside bulk materials (powders or polycrystals). The method is based on diffraction with hard X-rays (E>50 keV), enabling 3D studies of millimeter to centimeter-thick specimens. The position, volume, orientation, and elastic strain can be determined in hundreds of grains simultaneously. Furthermore, the evolution of the plastic strain can be characterised from grain rotations. Likewise, for coarse-grained materials, the topography of the grain boundaries can be mapped. The status of the technique is presented and the potential for in situ processing studies illustrated. The hard-X-ray method is compared to conventional neutron-diffraction techniques: texture and strain measurements, small-angle scattering, and in situ powder diffraction. (orig.)

  10. Empirically testing vaterite structural models using neutron diffraction and thermal analysis

    Science.gov (United States)

    Chakoumakos, Bryan C.; Pracheil, Brenda M.; Koenigs, Ryan P.; Bruch, Ronald M.; Feygenson, Mikhail

    2016-11-01

    Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite—a metastable polymorph of CaCO3. Vaterite is an important material ranging from biomedical to personal care applications although its crystal structure is highly debated. We characterized the structure of Lake Sturgeon otoliths using thermal analysis and neutron powder diffraction, which is used non-destructively. We confirmed that while Lake Sturgeon otoliths are primarily composed of vaterite, they also contain the denser CaCO3 polymorph, calcite. For the vaterite fraction, neutron diffraction data provide enhanced discrimination of the carbonate group compared to x-ray diffraction data, owing to the different relative neutron scattering lengths, and thus offer the opportunity to uniquely test the more than one dozen crystal structural models that have been proposed for vaterite. Of those, space group P6522 model, a = 7.1443(4)Å, c = 25.350(4)Å, V = 1121.5(2)Å3 provides the best fit to the neutron powder diffraction data, and allows for a structure refinement using rigid carbonate groups.

  11. Empirically testing vaterite structural models using neutron diffraction and thermal analysis.

    Science.gov (United States)

    Chakoumakos, Bryan C; Pracheil, Brenda M; Koenigs, Ryan P; Bruch, Ronald M; Feygenson, Mikhail

    2016-11-18

    Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite-a metastable polymorph of CaCO3. Vaterite is an important material ranging from biomedical to personal care applications although its crystal structure is highly debated. We characterized the structure of Lake Sturgeon otoliths using thermal analysis and neutron powder diffraction, which is used non-destructively. We confirmed that while Lake Sturgeon otoliths are primarily composed of vaterite, they also contain the denser CaCO3 polymorph, calcite. For the vaterite fraction, neutron diffraction data provide enhanced discrimination of the carbonate group compared to x-ray diffraction data, owing to the different relative neutron scattering lengths, and thus offer the opportunity to uniquely test the more than one dozen crystal structural models that have been proposed for vaterite. Of those, space group P6522 model, a = 7.1443(4)Å, c = 25.350(4)Å, V = 1121.5(2)Å(3) provides the best fit to the neutron powder diffraction data, and allows for a structure refinement using rigid carbonate groups.

  12. Ellipsometric and neutron diffraction study of pentane physisorbed on graphite.

    Science.gov (United States)

    Kruchten, Frank; Knorr, Klaus; Volkmann, Ulrich G; Taub, Haskell; Hansen, Flemming Y; Matthies, Blake; Herwig, Kenneth W

    2005-08-02

    High-resolution ellipsometry and neutron diffraction measurements have been used to investigate the structure, growth, and wetting behavior of fluid pentane (n-C(5)H(12)) films adsorbed on graphite substrates. We present isotherms of the thickness of pentane films adsorbed on the basal-plane surfaces of a pyrolytic graphite substrate as a function of the vapor pressure. These isotherms are measured ellipsometrically for temperatures between 130 and 190 K. We also describe neutron diffraction measurements in the temperature range 11-140 K on a deuterated pentane (n-C(5)D(12)) monolayer adsorbed on an exfoliated graphite substrate. Below a temperature of 99 K, the diffraction patterns are consistent with a rectangular centered structure. Above the pentane triple point at 143.5 K, the ellipsometric measurements indicate layer-by-layer adsorption of at least seven fluid pentane layers, each having the same optical thickness. Analysis of the neutron diffraction pattern of a pentane monolayer at a temperature of 130 K is consistent with small clusters having a rectangular-centered structure and an area per molecule of approximately 37 A(2) in coexistence with a fluid monolayer phase. Assuming values of the polarizability tensor from the literature and that the monolayer fluid has the same areal density as that inferred for the coexisting clusters, we calculate an optical thickness of the fluid pentane layers in reasonable agreement with that measured by ellipsometry. We discuss how these results support the previously proposed "footprint reduction" mechanism of alkane monolayer melting. In the hypercritical regime, we show that the layering behavior is consistent with the two-dimensional Ising model and determine the critical temperatures for layers n = 2-5.

  13. Neutron Diffraction Studies of Intercritically Austempered Ductile Irons

    Energy Technology Data Exchange (ETDEWEB)

    Druschitz, Alan [University of Alabama, Birmingham; Aristizabal, Ricardo [University of Alabama, Birmingham; Druschitz, Edward [University of Alabama, Birmingham; Hubbard, Camden R [ORNL; Watkins, Thomas R [ORNL

    2011-01-01

    Neutron diffraction is a powerful tool that can be used to identify the phases present and to measure the spacing of the atomic planes in a material. Thus, the residual stresses can be determined within a component and/or the phases present. New intercritically austempered irons rely on the unique properties of the austenite phase present in their microstructures. If these materials are to see widespread use, methods to verify the quality (behavior consistency) of these materials and to provide guidance for further optimization will be needed. Neutron diffraction studies were performed at the second generation neutron residual stress facility (NRSF2) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory on a variety of intercritically austempered irons. For similar materials, such as TRIP steels, the strengthening mechanism involves the transformation of metastable austenite to martensite during deformation. For the intercritically austempered ductile irons two different deformation/strengthening mechanisms, phase transformation and slip, dependent upon the iron chemistry, were observed. Lattice strain and phase fraction data as a function of applied stress are presented.

  14. Stress analysis by neutron diffraction. Spannungsanalyse mit Neutronenbeugung

    Energy Technology Data Exchange (ETDEWEB)

    Pintschovius, L. (Kernforschungszentrum Karlsruhe, INFP (Germany))

    1992-01-01

    Investigating mechanical stresses, the point of interest actually is not the interplanar crystal spacing itself in the polycrystalline material, but the relative change of it. Neutrons are particularly suited for application to stress analysis, due to their deep penetration range in the materials of up to 10 mm. The article explains the basic principles of operation of a neutron diffractometer and its application to analysing residual stresses in specimens made of aluminium alloys or ceramics, in steel-ceramic soldered joints, or in steel rivets. (DG).

  15. Refractive and diffractive neutron optics with reduced chromatic aberration

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Poulsen, Henning Friis; Bentley, P.M.

    2014-01-01

    by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness...... path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams....... to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam...

  16. Polarized neutron diffraction study of CePd{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Givord, F.; Galera, R.M.; Murani, A.P.; Lelievre-Berna, E

    2004-07-15

    We have performed polarized neutron diffraction measurements on the intermediate valence compound CePd{sub 3} using the D3 spectrometer at the ILL. The results show that at low temperatures, 1.7 K, as well as at 100 K, the field-induced magnetic amplitudes measured in a field of 4.6 T could be interpreted in terms of two contributions: a 4f-type contribution with a Ce{sup 3+} form factor, and an extra delocalized contribution (relatively narrow in q-extent). In particular, we find that the values of the 4f moment deduced from the extrapolation of the neutron data to Q=0 are systematically lower than the values deduced from bulk magnetization measurements performed on the same sample. This difference can be ascribed to a possible positive polarization of the conduction band which is similar at both temperatures.

  17. Oxygen as a site specific structural probe in neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Neuefeind, Joerg C [ORNL; Simonson, J Michael {Mike} [ORNL; Salmon, Phil [University of Bath; Zeidler, Anita [University of Bath; Fischer, Henry E [Institut Laue-Langevin (ILL); Rauch, Helmut [E141 Atominstitut der & #xD6; sterreichischen Universit& #xE4; ten,; Markland, Thomas [Columbia University; Lemmel, Hartmut [Technical University Vienna

    2011-01-01

    Oxygen is a ubiquitous element, playing an essential role in most scientific and technological disciplines, and is often incorporated within a structurally disordered material where examples include molten silicates in planetary science, glasses used for lasers and optical communication, and water in biological processes. Establishing the structure of a liquid or glassy oxide and thereby its relation to the functional properties of a material is not, however, a trivial task owing to the complexity associated with atomic disorder. Here we approach this challenge by measuring the bound coherent neutron scattering lengths of the oxygen isotopes with the sensitive technique of neutron interferometry. We find that there is a small but finite contrast of 0.204(6) fm between the scattering lengths of the isotope 18O and oxygen of natural isotopic abundance natO, contrary to tables of recommended values. This has enabled us to investigate the structure of both light and heavy water by exploiting, for the first time, the method of oxygen isotope substitution in neutron diffraction, thus circumventing many of the significant problems associated with more traditional methods in which hydrogen is substituted by deuterium. We find a difference of ~0.5% between the O-H and O-D intra-molecular bond distances which is much smaller than recent estimates based on diffraction data and is found to be in excellent agreement with path integral molecular dynamics simulations made with a flexible polarisable water model. Our results demonstrate the potential for using oxygen isotope substitution as a powerful and effective site specific probe in a plethora of materials, of pertinence as instrumentation at next generation neutron sources comes online

  18. Neutron powder diffraction study of 239PuD x

    Science.gov (United States)

    Bartscher, W.; Boeuf, A.; Caciuffo, R.; Fournier, J. M.; Haschke, J. M.; Manes, L.; Rebizant, J.; Rustichelli, F.; Ward, J. W.

    1985-05-01

    A neutron powder diffraction study has been carried out on several deuterids of Plutonium (PuD 2.25,PuD 2.33, PuD 2.65) to determine the positions of deuterium atoms in the host metal f.c.c. lattice. It has been found that vacancies occur in the tetrahedral sites. Moreover, with increasing deuterium concentration, octahedral interstitial deuterium atoms are displaced from their ideal positions. These results can be explained by the formation of clusters. Finally, at low temperature, these compounds become ferromagnetically ordered. An ordered magnetic moment μ 0≈0.8 μ B has been measured on all compounds.

  19. A neutron diffraction study of RMn2O5 multiferroics

    Science.gov (United States)

    Radaelli, P. G.; Chapon, L. C.

    2008-10-01

    The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.

  20. Structure of molten yttrium aluminates: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Cristiglio, V [Centre de Recherche sur les Materiaux a Haute Temperature, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Hennet, L [Centre de Recherche sur les Materiaux a Haute Temperature, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Cuello, G J [Institut Laue-Langevin, 6 rue Jules Horowitz, BP48 Grenoble cedex 9 (France); Pozdnyakova, I [Centre de Recherche sur les Materiaux a Haute Temperature, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Johnson, M R [Institut Laue-Langevin, 6 rue Jules Horowitz, BP48 Grenoble cedex 9 (France); Fischer, H E [Institut Laue-Langevin, 6 rue Jules Horowitz, BP48 Grenoble cedex 9 (France); Zanghi, D [Centre de Recherche sur les Materiaux a Haute Temperature, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Van, Q Vu [Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ (United Kingdom); Wilding, M C [Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ (United Kingdom); Greaves, G N [Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ (United Kingdom); Price, D L [Centre de Recherche sur les Materiaux a Haute Temperature, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France)

    2007-10-17

    We used the aerodynamic levitation technique combined with CO{sub 2} laser heating to study the structure of liquid yttrium aluminates above their melting point with neutron diffraction. For various yttria contents, we determined the structure factors and corresponding pair correlation functions describing the short-range order in the liquids. In particular, we derived Al-O and Y-O bond distances and coordination numbers. Experimental data are compared with ab initio molecular dynamics, carried out using the VASP code where the interatomic forces are obtained from density functional theory. In particular, partial pair correlation functions have been calculated and are in relatively good agreement with the experimental observations.

  1. Neutron diffraction study on liquid Al-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, Sascha; Marczinke, Jennifer; Hoyer, Walter [Technische Univ. Chemnitz-Zwickau, Chemnitz (Germany). Inst. fuer Physik; Hennet, Louis [CNRS-CEMHTI, Orleans Univ. (France); Cuello, Gabriel Julio [Institute Laue - Langevin, Grenoble (France); Basque Country Univ., Bilbao (Spain)

    2010-06-15

    A neutron diffraction study on liquid Al-Ni alloys close to the liquidus temperature is presented. By applying an aerodynamic levitation technique associated with CO{sub 2} laser heating, it was possible to investigate the high-melting alloys around the equi-atomic composition, too. We observe a change in the local chemical atomic arrangement from preferred environing of like atoms in Al-rich alloys to hetero-coordination in the Ni-rich alloys. It is furthermore demonstrated that the apparent pre-peak can be attributed to a distinct Ni-Ni short-range order. (orig.)

  2. Neutron diffraction study of U-10 wt% Mo alloy

    Science.gov (United States)

    Seong, Baek-Seok; Lee, Chang-Hee; Lee, Jeong-Soo; Shim, Hae-Seop; Lee, Jin-Ho; Kim, Ki Hwan; Kim, Chang Kyu; Em, Vyacheslav

    2000-01-01

    The structural properties of a U-10 wt% Mo powder sample prepared by the centrifugal atomization method were investigated by the Rietveld total profile analysis method. The high resolution neutron powder diffractometer at the HANARO research reactor in Taejon, Korea, was used for a series of neutron diffraction pattern measurements for the study. The sample was synthesized by the centrifugal atomization method and was found to consist of two γ-U solid solution phases having identical bcc structures, but slightly different lattice dimensions, and accordingly different Mo content. When the sample was annealed for 10 h at 600°C, the two solid solution phases with different Mo contents merged into a uniform single phased γ-U solid solution. The diffraction pattern of the annealed sample showed two additional weak reflections, which could be indexed as a super lattice structure U 3Mo derived from the bcc cell by a /1 1 0/-1 1 0/0 0 1/ type lattice transformation. The disorder-order phase transition leading to the formation of ordered metastable phase U 3Mo should be of the first-order.

  3. In-Situ Studies of Intercritically Austempered Ductile Iron Using Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Druschitz, Alan [University of Alabama, Birmingham; Aristizabal, Ricardo [University of Alabama, Birmingham; Druschitz, Edward [University of Alabama, Birmingham; Hubbard, Camden R [ORNL; Watkins, Thomas R [ORNL; Walker, Larry R [ORNL; Ostrander, M [Rex Heat Treat, Anniston, AL

    2012-01-01

    Intercritically austempered ductile irons hold promise for applications requiring fatigue durability, excellent castability, low production energy requirements, reduced greenhouse gas emissions and excellent machinability. In the present study, four different ductile iron alloys, containing manganese and nickel as the primary austenite-stabilizing elements, were heat treated to obtain different quantities of austenite in the final microstructure. This paper reports the microstructures and phases present in these alloys. Further, lattice strains and diffraction elastic constants in various crystallographic directions and the transformation characteristics of the austenite as a function of applied stress were determined using in-situ loading with neutron diffraction at the second generation Neutron Residual Stress Facility (NRSF2) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL).

  4. In Situ Studies of Intercritically Austempered Ductile Iron Using Neutron Diffraction

    Science.gov (United States)

    Druschitz, Alan P.; Aristizabal, Ricardo E.; Druschitz, Edward; Hubbard, C. R.; Watkins, Thomas R.; Walker, L.; Ostrander, Mel

    2012-05-01

    Intercritically austempered ductile irons hold promise for applications requiring fatigue durability, excellent castability, low production energy requirements, reduced greenhouse gas emissions, and excellent machinability. In the present study, four different ductile iron alloys, containing manganese and nickel as the primary austenite-stabilizing elements, were heat treated to obtain different quantities of austenite in the final microstructure. This article reports the microstructures and phases present in these alloys. Furthermore, lattice strains and diffraction elastic constants in various crystallographic directions and the transformation characteristics of the austenite were determined as a function of applied stress using in situ loading during neutron diffraction at the second generation Neutron Residual Stress Facility at the High Flux Isotope Reactor at Oak Ridge National Laboratory.

  5. In situ neutron diffraction under high pressure—Providing an insight into working catalysts

    Science.gov (United States)

    Kandemir, Timur; Wallacher, Dirk; Hansen, Thomas; Liss, Klaus-Dieter; Naumann d'Alnoncourt, Raoul; Schlögl, Robert; Behrens, Malte

    2012-05-01

    In the present work the construction and application of a continuous flow cell is presented, from which neutron diffraction data could be obtained during catalytic reactions at high pressure. By coupling an online gas detection system, parallel structure and activity investigations of working catalysts under industrial relevant conditions are possible. The flow cell can be operated with different feed gases in a wide range from room temperature to 603 K. Pressures from ambient up to 6 MPa are applicable. An exchangeable sample positioning system makes the flow cell suitable for several different goniomter types on a variety of instrument beam lines. Complementary operational test measurements were carried out monitoring reduction of and methanol synthesis over a Cu/ZnO/Al2O3 catalyst at the high-flux powder diffraction beamline D1B at ILL and high-resolution diffraction beamline Echidna at ANSTO.

  6. A New Approach of Quantum Mechanics for Neutron Single-Slit Diffraction

    Institute of Scientific and Technical Information of China (English)

    WU Xiang-Yao; YANG Jing-Hai; LIU Xiao-Jing; WANG Li; LIU Bing; FAN Xi-Hui; GUO Yi-Qing

    2007-01-01

    Phenomena of electron, neutron, atomic and molecular diffraction have been studied in many experiments, and these experiments are explained by many theoretical works. We study neutron single-slit diffraction with a quantum mechanical approach. It is found that the obvious diffraction patterns can be obtained when the singleslit width a is in the range of 3λ~ 60λ. We also find a new quantum effect of the thickness of single-slit which can make a large impact on the diffraction pattern. The new quantum effect predicted in our work can be tested by the neutron single-slit diffraction experiment.

  7. A neutron diffraction study of ancient Greek ceramics

    Science.gov (United States)

    Siouris, I. M.; Walter, J.

    2006-11-01

    Non-destructive neutron diffraction studies were performed on three 2nd-century BC archaeological pottery fragments from the excavation site of Neos Scopos, Serres, in North Greece. In all the 273 K diagrams quartz and feldspars phase fractions are dominant. Diopside and iron oxide phases were also identifiable. The diopside content is found to decrease with increasing quartz-feldspar compositions. Iron oxides containing minerals were found to be present and the phase compositions reflect upon the coloring of the samples. However, the different content compositions of the phases may suggest different regions of the original clay materials as well as different preparation techniques. The firing temperatures were determined to be in the range of 900-1000 °C.

  8. A neutron diffraction study of ancient Greek ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Siouris, I.M. [Department of Informatics and Communication, Technological and Educational, Institute of Serres, SimLab, 62 124 Serres (Greece)]. E-mail: siouris@demo.cc.duth.gr; Walter, J. [Mineralogisch-Petrologisches Institut, Universitaet Bonn, D-53115 Bonn (Germany)

    2006-11-15

    Non-destructive neutron diffraction studies were performed on three 2nd-century BC archaeological pottery fragments from the excavation site of Neos Scopos, Serres, in North Greece. In all the 273 K diagrams quartz and feldspars phase fractions are dominant. Diopside and iron oxide phases were also identifiable. The diopside content is found to decrease with increasing quartz-feldspar compositions. Iron oxides containing minerals were found to be present and the phase compositions reflect upon the coloring of the samples. However, the different content compositions of the phases may suggest different regions of the original clay materials as well as different preparation techniques. The firing temperatures were determined to be in the range of 900-1000 deg. C.

  9. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  10. Principles of the measurement of residual stress by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Webster, G.A.; Ezeilo, A.N. [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Mechanical Engineering

    1996-11-01

    The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs.

  11. Neutrons in studies of phospholipid bilayers and bilayer–drug interaction. I. Basic principles and neutron diffraction

    Directory of Open Access Journals (Sweden)

    Belička M.

    2014-12-01

    Full Text Available In our paper, we demonstrate several possibilities of using neutrons in pharmaceutical research with the help of examples of scientific results achieved at our University. In this first part, basic properties of neutrons and elementary principles of elastic scattering of thermal neutrons are described. Results of contrast variation neutron diffraction on oriented phospholipid bilayers with intercalated local anaesthetic or cholesterol demonstrate the potential of this method at determination of their position in bilayers. Diffraction experiments with alkan-1-ols located in the bilayers revealed their influence on bilayer thickness as a function of their alkyl chain length.

  12. Neutron Diffraction Studies of the Modulated Magnetic Structures of CeSb and Nd Metal

    DEFF Research Database (Denmark)

    Lebech, Bente

    1981-01-01

    The magnetic phase diagram of CeSb, which has been determined by neutron diffraction and other experimental techniques, is briefly reviewed and related to some of the theoretical models that have been developed to account for it. The results of neutron diffraction studies of Nd metal are also...

  13. Novel diamond cells for neutron diffraction using multi-carat CVD anvils.

    Science.gov (United States)

    Boehler, R; Molaison, J J; Haberl, B

    2017-08-01

    Traditionally, neutron diffraction at high pressure has been severely limited in pressure because low neutron flux required large sample volumes and therefore large volume presses. At the high-flux Spallation Neutron Source at the Oak Ridge National Laboratory, we have developed new, large-volume diamond anvil cells for neutron diffraction. The main features of these cells are multi-carat, single crystal chemical vapor deposition diamonds, very large diffraction apertures, and gas membranes to accommodate pressure stability, especially upon cooling. A new cell has been tested for diffraction up to 40 GPa with an unprecedented sample volume of ∼0.15 mm(3). High quality spectra were obtained in 1 h for crystalline Ni and in ∼8 h for disordered glassy carbon. These new techniques will open the way for routine megabar neutron diffraction experiments.

  14. Neutron scatter and diffraction techniques applied to nucleosome and chromatin structure.

    Science.gov (United States)

    Bradbury, E M; Baldwin, J P

    1986-12-01

    Neutron scatter and diffraction techniques have made substantial contributions to our understanding of the structure of the nucleosome, the structure of the 10-nm filament, the "10-nm----30-nm" filament transition, and the structure of the "34-nm" supercoil or solenoid of nucleosomes. Neutron techniques are unique in their properties, which allows for the separation of the spatial arrangements of histones and DNA in nucleosomes and chromatin. They have equally powerful applications in structural studies of any complex two-component biological system. A major success for the application of neutron techniques was the first clear proof that DNA was located on the outside of the histone octamer in the core particle. A full analysis of the neutron-scatter data gave the parameters of Table 3 and the low-resolution structure of the core particle in solution shown in Fig. 6. Initial low-resolution X-ray diffraction studies of core particle crystals gave a model with a lower DNA pitch of 2.7 nm. Higher-resolution X-ray diffraction studies now give a structure with a DNA pitch of 3.0 nm and a hole of 0.8 nm along the axis of the DNA supercoil. The neutron-scatter solution structure and the X-ray crystal structure of the core particle are thus in full agreement within the resolution of the neutron-scatter techniques. The model for the chromatosome is largely based on the structural parameters of the DNA supercoil in the core particle, nuclease digestion results showing protection of a 168-bp DNA length by histone H1 and H1 peptide, and the conformational properties of H1. The path of the DNA outside the chromatosome is not known, and this information is crucial for our understanding of higher chromatin structure. The interactions of the flexible basic and N- and C-terminal regions of H1 within chromatin and how these interactions are modulated by H1 phosphorylation are not known. The N- and C-terminal regions of H1 represent a new type of protein behavior, i.e., extensive

  15. Residual stress in sprayed Ni+5%Al coatings determined by neutron diffraction

    CERN Document Server

    Matejicek, J; Gnaeupel-Herold, T; Prask, H J

    2002-01-01

    Coatings of nickel-based alloys are used in numerous high-performance applications. Their properties and lifetimes are influenced by factors such as residual stress. Neutron diffraction is a powerful tool for nondestructive residual stress determination. In this study, through-thickness residual stress profiles in Ni+5%Al coatings on steel substrates were determined. Two examples of significantly different spraying techniques - plasma spraying and cold spraying - are highlighted. Different stress-generation mechanisms are discussed with respect to process parameters and material properties. (orig.)

  16. Neutron diffraction study of metal-matrix composite with fullerite

    Science.gov (United States)

    Borisova, P. A.; Blanter, M. S.; Brazhkin, VV; Somenkov, VA; Filonenko, V. P.

    2016-09-01

    Interaction of amorphous fullerite C60 with austenitic Fe-33.2 wt. % Ni alloy at pressures 0-8 GPa and temperatures 600-1100 °C was studied by neutron diffraction. The amorphous fullerite was obtained by ball milling and mixed with the powder of the crystalline alloy. The interaction at sintering led to the dissolution of carbon in fcc Fe-Ni solid solution and the formation of carbide (Fe, Ni)3C, but the Fe-Ni-C alloy did not undergo phase transformations and preserved the original fcc structure. As a result, the alloy hardened, we could also witness a clear barometric effect: at the pressure of 2 GPa the amount of the dissolved carbon and the microhardness turned out to be significantly higher than those at 8 GPa. During sintering amorphous fullerite is undergoing phase transitions and its microhardness is higher than the microhardness of the metal component. At high temperatures of interaction graphite appears. The presence of Fe-Ni alloy in the composite reduces the temperature of graphite formation in comparison with transformations in the pure amorphous fullerene.

  17. Neutron diffraction studies for realtime leaching of catalytic Ni

    Energy Technology Data Exchange (ETDEWEB)

    Iles, Gail N., E-mail: gail.iles@helmholtz-berlin.de; Reinhart, Guillaume, E-mail: guillaume.reinhart@im2np.fr [European Space Agency, Keplerlaan 1, 2201 AZ Noordwijk (Netherlands); Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble (France); European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble (France); Devred, François, E-mail: fdevred@ulb.ac.be [Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden (Netherlands); Henry, Paul F., E-mail: paul.henry@esss.se; Hansen, Thomas C., E-mail: hansen@ill.fr [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble (France)

    2014-07-21

    The leaching of Al from intermetallic samples of Nickel Aluminium alloys to form Raney-type nickel catalysts is widely used in the hydrogenation industry, however, little is known of the leaching process itself. In this study, the leaching of Al was measured in realtime, in situ, using the high-flux powder neutron diffractometer, D20, at the Institut Laue-Langevin. Despite the liberation of hydrogen and effervescent nature of the reaction the transformation of the dry powder phases into Raney-type Ni was determined. Samples produced by gas-atomisation were found to leach faster than those produced using the cast and crushed technique. Regardless of processing route of the precursor powder, the formation of spongy-Ni occurs almost immediately, while Ni{sub 2}Al{sub 3} and NiAl{sub 3} continue to transform over longer periods of time. Small-angle scattering and broadening of the diffraction peaks is an evidence for the formation of the smaller Ni particles. Understanding the kinetics of the leaching process will allow industry to refine production of catalysts for optimum manufacturing time while knowledge of leaching dynamics of powders produced by different manufacturing techniques will allow further tailoring of catalytic materials.

  18. Powder Neutron Diffraction Study of HoCoGa5

    Energy Technology Data Exchange (ETDEWEB)

    Kabayashi, Riki [Japan Atomic Energy Agency (JAEA); Kaneko, Koji [Japan Atomic Energy Agency (JAEA); Wakimoto, Shuichi [Japan Atomic Energy Agency (JAEA); Chi, Songxue [ORNL; Sanada, Naoyuki [Yokohama National University; Watanuki, Ryuta [Yokohama National University; Suzuki, Kazuya [Yokohama National University

    2013-01-01

    We have studied successive magnetic transitions of HoCoGa5 at TN1 = 9.6 K and TN2 = 7.5 K by using powder neutron diffraction. Apparent superlattice peaks were observed at temperatures below TN1. With further decreases temperature, the patterns exhibit a substantial change at temperatures below TN2. The observed magnetic peaks at 8 K (AntiFerromagnetic InCommensurate (AFIC) phase : TN2 < T < TN1) can be represented by the propagation vector qL = (1/2 0 ) with = 0.35(2). In contrast, the magnetic structure becomes commensurate with qC = (1/2 0 1/2) at 4 K (AntiFerromagnetic Commensurate (AFC) phase : T < TN2). The temperature dependence of magnetic intensity shows an apparent temperature hysteresis at TN2, indicates a first-order transition at TN2. Analysis of the integrated intensity at 4 K reveals that the Ho moment with a size of 8.6(2) B, oriented parallel to the c-axis in the AFC phase. While the successive transitions of HoCoGa5 are different from those of TbCoGa5, the magnetic structure in the AFC phase of HoCoGa5 is the same as the AFTb I of TbCoGa5, and may indicate an additional transition at a lower temperature in HoCoGa5.

  19. Real-time observations of lithium battery reactions-operando neutron diffraction analysis during practical operation.

    Science.gov (United States)

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-06-30

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries.

  20. Real-time observations of lithium battery reactions—operando neutron diffraction analysis during practical operation

    Science.gov (United States)

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-06-01

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries.

  1. Real-time observations of lithium battery reactions—operando neutron diffraction analysis during practical operation

    Science.gov (United States)

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-01-01

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries. PMID:27357605

  2. Study on Destructuring effect of trehalose on water by neutron diffraction

    CERN Document Server

    Branca, C; Migliardo, F; Magazù, V; Soper, A K

    2002-01-01

    In this work results on trehalose/water solutions by neutron diffraction are reported. The study of the partial structure factors and spatial distribution functions gives evidence of a decreasing tetrahedrality degree of water and justifies its cryoprotectant effectiveness. (orig.)

  3. Neutron Diffraction and Magnetostriction of Cubic La(FexAl1-x)13 Intermetallic Compounds

    NARCIS (Netherlands)

    Palstra, T.T.M.; Nieuwenhuys, G.J.; Mydosh, J.A.; Helmholdt, R.B.; Buschow, K.H.J.

    1986-01-01

    The ferromagnetic and antiferromagnetic states of La(FexAl1-x)13 were studied by neutron diffraction and magnetostriction measurements. We present a model for the magnetic structure of the antiferromagnetic state, consisting of ferromagnetic clusters, coupled antiferromagnetically. Magnetostriction

  4. Neutron scattering and diffraction instrument for structural study on biology in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Ibaraki-ken (Japan)

    1994-12-31

    Neutron scattering and diffraction instruments in Japan which can be used for structural studies in biology are briefly introduced. Main specifications and general layouts of the instruments are shown.

  5. High-resolution neutron diffraction studies of biological and industrial fibres

    Energy Technology Data Exchange (ETDEWEB)

    Langan, P.; Mason, S.A. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Shotton, M.; Simpson, L. [Keele Univ. (United Kingdom); Grimm, H. [FZ, Juelich (Germany); Leberman, R. [EMBL, (Country Unknown)

    1997-04-01

    Neutron diffraction is becoming an important tool for studying fibres due to its complementarity to X-ray diffraction. Unlike X-rays, scattering of neutrons by polymer atoms is not a function of their atomic number. In high-resolution studies (1.5-3 A) on D19 deuteration (replacing H by D) is being used to change the relative scattering power of chosen groups making them easier to locate. Recent studies on DNA and cellulose are described. (author). 6 refs.

  6. Verification of the weak equivalence principle with Laue diffracting neutrons: Test experiment

    Science.gov (United States)

    Vezhlev, E. O.; Voronin, V. V.; Kuznetsov, I. A.; Semenikhin, S. Yu.; Fedorov, V. V.

    2013-07-01

    We propose a novel experiment to test the weak equivalence principle (WEP) for the Laue diffracting neutron. Our experiment is based on an essential magnification of an external affect on neutron diffracting by Laue for the Bragg angles close to the right one in couple with additional enhancement factor which exists due to the delay of the Laue diffracting neutron at such Bragg angles. This enhancement phenomena is proposed to be utilized for measuring the force which deviates from zero if WEP is violated. The accuracy of measuring inertial to gravitational neutron masses ratio for the introduced setup can reach ˜10-5, which is more than one order superior to the best present-day result.

  7. Molecular conformation and structural correlations of liquid D-1-propanol through neutron diffraction

    Indian Academy of Sciences (India)

    A Sahoo; S Sarkar; P S R Krishna; V Bhagat; R N Joarder

    2008-07-01

    An analysis of neutron diffraction data of liquid deuterated 1-propanol at room temperature to extract its molecular conformation is presented. Being a big molecule with twelve atomic sites, the analysis is tricky and needs careful consideration. The resulting molecular parameters are compared with electron diffraction (gas phase), X-ray diffraction (liquid phase) and MD simulation results. Information about the hydrogen-bonded intermolecular structure in liquid is extracted and nature of the probable molecular association suggested.

  8. X-Ray and Neutron Diffraction Studies on Thermal Parameters of Thalous Bromide

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Thermal parameters of TIBr were determined using both X-ray and neutron diffraction techniques. The data was analysed by Rietveld profile refinement procedure. From the neutron diffraction data, due to weak odd-order reflections, it was not possible to determine the individual thermal parameters. The X-ray diffraction measurements yielded BT1=0.296(5) nm2 and BBr=0.162(5) nm2. The overall isotropic value, B was 0.252(7) nm2 which is in good agreement with B=0.230(8) nm2 obtained from present neutron diffraction measurements. The present values are also in good agreement with theoretical estimates obtained from the shell models.

  9. X-ray diffraction: instrumentation and applications.

    Science.gov (United States)

    Bunaciu, Andrei A; Udriştioiu, Elena Gabriela; Aboul-Enein, Hassan Y

    2015-01-01

    X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. X-ray diffraction peaks are produced by constructive interference of a monochromatic beam of X-rays scattered at specific angles from each set of lattice planes in a sample. The peak intensities are determined by the distribution of atoms within the lattice. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. This review summarizes the scientific trends associated with the rapid development of the technique of X-ray diffraction over the past five years pertaining to the fields of pharmaceuticals, forensic science, geological applications, microelectronics, and glass manufacturing, as well as in corrosion analysis.

  10. Neutron diffraction facility for internal stress measurements at JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Yoshinori; Minakawa, Nobuaki; Morii, Yukio [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1997-06-01

    The Neutron Diffractometer for Residual Stress Analysis (RESA) is a two axis type neutron diffractometer with a goniometer controllable to specimen position in high precision for spatial distribution measurement of residual stress and with one- and zero-dimensional detectors, and has a characteristics of providing a pin-hole type neutron ray diaphragm to obtain local informations of the specimen. It is elucidated from the reported examples that the RESA in JAERI has a capacity of sufficient detection to a local strain with 10{sup -3} to 10{sup -4}. The residual stress measurement in JAERI is just in beginning state, and has many necessities to do a lot of trial measurements on various materials in future. And, when finishing the construction of pulsed neutron source under planning in JAERI, it can be expected to realize a neutron intensity of more than one hundred for the residual stress measurement and to construct a powerful measurement instrument in combination with introduction of testing method for TOF. (G.K.)

  11. Measurement of the neutron electric dipole moment by crystal diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fedorov, V.V. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Jentschel, M. [Institut Laue-Langevin, Grenoble (France); Kuznetsov, I.A.; Lapin, E.G. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Lelievre-Berna, E.; Nesvizhevsky, V.; Petoukhov, A. [Institut Laue-Langevin, Grenoble (France); Semenikhin, S.Yu. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Soldner, T.; Tasset, F. [Institut Laue-Langevin, Grenoble (France); Voronin, V.V., E-mail: vvv@pnpi.spb.r [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Braginetz, Yu.P. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation)

    2009-12-11

    An experiment using a prototype setup to search for the neutron electric dipole moment by measuring spin rotation in a non-centrosymmetric crystal (quartz) was carried out to investigate statistical sensitivity and systematic effects of the method. It has been demonstrated that the concept of the method works. The preliminary result of the experiment is d{sub n}=(2.5+-6.5)x10{sup -24}ecm. The experiment showed that an accuracy of approx2.5x10{sup -26}ecm can be obtained in 100 days data taking, using available quartz crystals and neutron beams.

  12. Measurement of the neutron electric dipole moment by crystal diffraction

    CERN Document Server

    Fedorov, V V; Kuznetsov, I A; Lapin, E G; Lelievre-Berna, E; Nesvizhevsky, V; Petoukhov, A; Semenikhin, S Yu; Soldner, T; Tasset, F; Voronin, V V; Braginetz, Yu P

    2009-01-01

    An experiment using a prototype setup to search for the neutron electric dipole moment by measuring spin-rotation in a non-centrosymmetric crystal (quartz) was carried out to investigate statistical sensitivity and systematic effects of the method. It has been demonstrated that the concept of the method works. The preliminary result of the experiment is $d_{\\rm n}=(2.5\\pm 6.5)\\cdot 10^{-24}$ e$\\cdot $cm. The experiment showed that an accuracy of $\\sim 2.5\\cdot 10^{-26}$ e$\\cdot $cm can be obtained in 100 days data taking, using available quartz crystals and neutron beams.

  13. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    CERN Document Server

    Hughes, D J; Heeley, E L

    2014-01-01

    Whilst the structural integrity and lifetime considerations in welded joints for blanket modules can be predicted using finite element software, it is essential to prove the validity of these simulations. This paper provides detailed analysis for the first time, of the residual stress state in a laser-welded sample with integral cooling channels. State-of-the-art non-destructive neutron diffraction was employed to determine the triaxial stress state and to understand microstructural changes around the heat affected zone. Synchrotron X-ray diffraction was used to probe the variation of strain-free lattice reference parameter around the weld zone allowing correction of the neutron measurements. This paper details an important experimental route to validation of predicted stresses in complex safety-critical reactor components for future applications.

  14. Investigation on Deformation Behavior of Nickel Aluminum Bronze by Neutron Diffraction and Transmission Electron Microscopy

    Science.gov (United States)

    Xu, Xiaoyan; Wang, Hong; Lv, Yuting; Lu, Weijie; Sun, Guangai

    2016-05-01

    The deformation behavior, deformation microstructures, and generated inter-phase stresses of nickel aluminum bronze were investigated by in situ neutron diffraction instrument and transmission electron microscopy in this paper. Lattice strains calculated by both peak shifting and broadening by Gaussian fitting of α and κ phase neutron diffraction peak profiles at both holding stress conditions and unloaded stress conditions were compared. Twining and stacking faults in α matrix were observed after deformed by different tensile stresses. Compressive internal/residual stress in α matrix and tensile internal stress in κ phase in elasto-plastic region were calculated based on neutron diffraction analysis. The piled-up dislocations around hard κ phases increase with increasing the deformation degree, which raise the stress concentration near α/ κ interface and increase the internal stresses.

  15. Observation of a strong interplanar electric field in a dynamical diffraction of polarized neutrons

    Science.gov (United States)

    Alexeev, V. L.; Fedorov, V. V.; Lapin, E. G.; Leushkin, E. K.; Rumiantsev, V. L.; Sumbaev, O. I.; Voronin, V. V.

    1989-11-01

    The first experimental study of the Schwinger interaction of polarized neutrons with an electric field of a noncentrosymmetric perfect crystal (α-quartz) was made for two wave dynamical diffraction. Phase shifts of Pendellösung fringes for two different spin to crystal field orientations were measured. The theory of the effect is given. The calculated value of SiO2 (11 overline20) interplanar electr field, seen by the diffracted neutron, is 2.1 × 10 8 V/cm. This is in good agreement with the experimental result: (1.8 ± 0.3) × 10 8 V/cm.

  16. FEM Analysis and Measurement of Residual Stress by Neutron Diffraction on the Dissimilar Overlay Weld Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2010-10-15

    Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods

  17. Characterisation of polycrystal deformation by numerical modelling and neutron diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, B.

    1997-09-01

    The deformation of polycrystals are modelled using three micron mechanic models; the Taylor model, the Sachs model and Hutchinson`s self-consistent (SC) model. The predictions of the rigid plastic Taylor and Sachs models are compared with the predictions of the SC model. As expected, the results of the SC model is about half-way between the upper- and lower-bound models. The influence of the elastic anisotropy is investigated by comparing the SC predictions for aluminium, copper and a hypothetical material (Hybrid) with the elastic anisotropy of copper and the Young`s modulus and hardening behaviour of aluminium. It is concluded that the effect of the elastic anisotropy is limited to the very early stages of plasticity, as the deformation pattern is almost identical for the three materials at higher strains. The predictions of the three models are evaluated by neutron diffraction measurements of elastic lattice strains in grain sub-sets within the polycrystal. The two rigid plastic models do not include any material parameters and therefore the predictions of the SC model is more accurate and more detailed than the predictions of the Taylor and Sachs models. The SC model is used to determine the most suitable reflection for technological applications of neutron diffraction, where focus is on the volume average stress state in engineering components. To be able to successfully to convert the measured elastic lattice strains for a specific reflection into overall volume average stresses, there must be a linear relation between the lattice strain of the reflection and the overall stress. According to the model predictions the 311-reflection is the most suitable reflection as it shows the smallest deviations from linearity and thereby also the smallest build-up of residual strains. The model predictions have pin pointed that the selection of the reflection is crucial for the validity of stresses calculated from the measured elastic lattice strains. (au) 14 tabs., 41

  18. Longe-Range Order in beta-Brass Studied by Neutron Diffraction

    DEFF Research Database (Denmark)

    Rathmann, Ole; Als-Nielsen, Jens Aage

    1974-01-01

    The long-range order, M(T), in β-brass has been measured by neutron diffraction from a small extinction-free crystal. The results agree with those obtained recently by x-ray diffraction. Near Tc our data are in accordance with a power law M(T)=D(1-T/Tc)β with the critical exponent β=0.293 as pred...

  19. Application of imaging plate neutron detector to neutron radiography

    CERN Document Server

    Fujine, S; Kamata, M; Etoh, M

    1999-01-01

    As an imaging plate neutron detector (IP-ND) has been available for thermal neutron radiography (TNR) which has high resolution, high sensitivity and wide range, some basic characteristics of the IP-ND system were measured at the E-2 facility of the KUR. After basic performances of the IP were studied, images with high quality were obtained at a neutron fluence of 2 to 7x10 sup 8 n cm sup - sup 2. It was found that the IP-ND system with Gd sub 2 O sub 3 as a neutron converter material has a higher sensitivity to gamma-ray than that of a conventional film method. As a successful example, clear radiographs of the flat view for the fuel side plates with boron burnable poison were obtained. An application of the IP-ND system to neutron radiography (NR) is presented in this paper.

  20. Direct measurement of the quartz c-axis using neutron diffraction

    Science.gov (United States)

    Hunter, Nicholas J. R.; Luzin, Vladimir; Wilson, Christopher J. L.

    2017-08-01

    Quartz c-axis pole figures are widely used across structural geology and geophysics to gain insights into crustal properties, yet their direct measurement using bulk diffraction techniques has hitherto been unsuccessful. In this contribution, we present measurements of the quartz c-axis using neutron diffraction. This has been achieved by combining advances in neutron diffraction instrumentation, high neutron fluxes and fast data acquisition, with carefully performed diffraction pattern analysis to resolve low intensity diffractions on the (003) diffraction peak hidden in the shoulder of the higher intensity (112) peak. These measurements have allowed us to assess 'recalculated' c-axis pole figures (i.e. those predicted from ODF functions) against measured c-axis pole figures, and thus assess the reliability of quartz c-axis pole figures past and present. We find that measured and recalculated pole figures are generally in good agreement in both strongly and weakly textured rocks, and that inclusion of the (003) pole figure into quartz texture analysis routines improves ODF construction.

  1. Neutron diffraction study of the magnetic structure of HoCu2

    DEFF Research Database (Denmark)

    Smetana, Z.; Sima, V.; Lebech, Bente

    1986-01-01

    Neutron diffraction measurements show that in the temperature range from 7.4 to TN=10.4 K the magnetic structure of HoCu2 is a commensurably modulated a-axis collinear structure with a wave vector q1=1/3a*. Below 7.4 K an additional structure component develops and the low temperature magnetic st...

  2. Zinc (tris) thiourea sulphate (ZTS): A single crystal neutron diffraction study

    Indian Academy of Sciences (India)

    P U Sastry; R Chitra; R R Choudhury; M Ramanadham

    2004-08-01

    The crystal structure of ZTS has been determined by neutron diffraction with a final -value of 0.026. Using the structural parameters, the contributions from the structural groups to the linear optical susceptibility and linear electro-optic coefficients have been evaluated. Results showed a significant contribution from the hydrogen bonds in the structure.

  3. Neutron diffraction from the vortex lattice in the heavy-fermion superconductor UPt3

    DEFF Research Database (Denmark)

    Kleiman, R.N.; Broholm, C.; Aeppli, G.

    1992-01-01

    We have used neutron diffraction to observe the vortex lattice of UPt3. This is the first such measurement in a heavy-fermion system, a superconductor below 1 K, or in a system with such a long magnetic penetration depth (6000 +/- 75 angstrom). It also provides the first value for the pair...

  4. Structure of liquid caesium-bismuth alloys studied by neutron diffraction

    NARCIS (Netherlands)

    van der Aart, SA; Verhoeven, VWJ; Verkerk, P; van der Lugt, W

    2000-01-01

    Neutron diffraction experiments were carried out for two liquid alloys with compositions CsBi and Cs3Bi2. The results indicate that probably polyanions with an average number of about two Bi atoms per cluster are formed. This result contrasts with that for liquid Cs-Sb, which contains larger chains

  5. Neutron diffraction study of KNO{sub 3} at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kirfel, A.; Zotov, N.; Schaefer, W

    2004-07-15

    High-temperature powder neutron diffraction measurements of KNO{sub 3} have shown co-existence of the {alpha}- and {beta}-phases in the temperature range 112-132 deg. C and presence of diffuse scattering in the {beta}-phase.

  6. Neutron diffraction investigation of liquid alkali metal-gallium alloys. Giant cluster formation?

    NARCIS (Netherlands)

    Alvarez, M; Lomba, E; Verkerk, P; van der Aart, SA; Bionducci, M; Mirebeau, [No Value; van der Lugt, W

    Neutron diffraction experiments were performed on the liquid alloys NaGa, NaGa3, KGa3 and CsGa3. The structure factors of KGa3 and CsGa3 display prepeaks at small wavenumbers (0.64 and 0.61 (A) over circle -1, respectively). This may indicate the existence of extremely large aggregates of atoms in

  7. Neutron Diffraction from the Second Layer of 4He on Graphite

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Passell, L.; Thomlinson, W.

    1981-01-01

    Neutron diffraction has been used to study the second atomic layer of **4He adsorbed on graphite. As the **4He-coverage exceeds the first layer, the second initially forms a fluid phase. But when there is enough **4He in the third layer to compress the second, this layer solidifies. The structure...

  8. Neutron diffraction investigation of liquid alkali metal-gallium alloys. Giant cluster formation?

    NARCIS (Netherlands)

    Alvarez, M; Lomba, E; Verkerk, P; van der Aart, SA; Bionducci, M; Mirebeau, [No Value; van der Lugt, W

    2002-01-01

    Neutron diffraction experiments were performed on the liquid alloys NaGa, NaGa3, KGa3 and CsGa3. The structure factors of KGa3 and CsGa3 display prepeaks at small wavenumbers (0.64 and 0.61 (A) over circle -1, respectively). This may indicate the existence of extremely large aggregates of atoms in t

  9. Through-Thickness Measurements of Residual Stresses in an Overlay Dissimilar Weld Pipe using Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Wan Chuck; EM, Vyacheslav; Lee, Ho Jin; Kim, Kang Soo; Kang, Mi Hyun; Joo, Jong Dae; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2010-10-15

    The distribution of residual stresses in dissimilar material joints has been extensively studied because of the wide applications of the dissimilar welds in many inevitable complex design structures. Especially the cracking of dissimilar welding has been a long standing issue of importance in many components of the power generation industries such as nuclear power plant, boiling pressure system, and steam generators. In particular, several failure analysis and direct observations have shown that critical fractures have frequently occurred in one side of the dissimilar welded parts. For example, the heat-affected zone on the ferrite steel side is known to critical in many dissimilar welding pipes when ferrite (low carbon steel) and austenite (stainless) steels are joined. The main cause of the residual stresses can be attributed to the mismatch in the coefficient of thermal expansion between the dissimilar metals (ferrite and austenite). Additional cladding over circumferential welds is known to reinforce the mechanical property due to the beneficial compressive residual stress imposed on the weld and heat-affected zone. However, science-based quantitative measurement of the through thickness residual stress distribution is very limited in literature. The deep penetration capability of neutrons into most metallic materials makes neutron diffraction a powerful tool to investigate and map the residual stresses of materials throughout the thickness and across the weld. Furthermore, the unique volume averaged bulk characteristic of materials and mapping capability in three dimensions are suitable for the engineering purpose. Thus, the neutron-diffraction measurement method has been selected as the most useful method for the study of the residual stresses in various dissimilar metal welded structures. The purpose of this study is to measure the distribution of the residual stresses in a complex dissimilar joining with overlay in the weld pipe. Specifically, we measured

  10. Protein crystallization and initial neutron diffraction studies of the photosystem II subunit PsbO.

    Science.gov (United States)

    Bommer, Martin; Coates, Leighton; Dau, Holger; Zouni, Athina; Dobbek, Holger

    2017-09-01

    The PsbO protein of photosystem II stabilizes the active-site manganese cluster and is thought to act as a proton antenna. To enable neutron diffraction studies, crystals of the β-barrel core of PsbO were grown in capillaries. The crystals were optimized by screening additives in a counter-diffusion setup in which the protein and reservoir solutions were separated by a 1% agarose plug. Crystals were cross-linked with glutaraldehyde. Initial neutron diffraction data were collected from a 0.25 mm(3) crystal at room temperature using the MaNDi single-crystal diffractometer at the Spallation Neutron Source, Oak Ridge National Laboratory.

  11. Characterization of a polychromatic neutron beam diffracted by pyrolytic graphite crystals

    CERN Document Server

    Byun, S H; Choi, H D

    2002-01-01

    The beam spectrum for polychromatic neutrons diffracted by pyrolytic graphite crystals was characterized. The theoretical beam spectrum was obtained using the diffraction model for a mosaic crystal. The lattice vibration effects were included in the calculation using the reported vibration amplitude of the crystal and the measured time-of-flight spectra in the thermal region. The calculated beam spectrum was compared with the results obtained in the absence of thermal motion. The lattice vibration effects became more important for the higher diffraction orders and a large decrease in the neutron flux induced by the vibrations was identified in the epithermal region. The validity of the beam spectrum was estimated by comparing with the effective quantities determined from prompt gamma-ray measurements and Cd-ratios measured both for 1/nu and non-1/nu nuclides.

  12. Neutron diffraction studies of magnetic-shape memory Ni-Mn-Ga single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Heczko, Oleg [Laboratory of Materials Science, Helsinki University of Technology, Vuorimiehentie 2A, P.O. Box 6200, FI-02015 TKK, Espoo (Finland)]. E-mail: oleg.heczko@tkk.fi; Prokes, Karel [Berlin Neutron Scattering Center, Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin (Wannsee) (Germany); Hannula, Simo-Pekka [Laboratory of Materials Science, Helsinki University of Technology, Vuorimiehentie 2A, P.O. Box 6200, FI-02015 TKK, Espoo (Finland)

    2007-09-15

    Neutron diffraction of single crystal of the typical example of magnetic-shape memory (MSM) alloy Ni{sub 49.7}Mn{sub 29.3}Ga{sub 21} was carried out with a 2D position sensitive detector. The quality and inhomogeneity of the single crystal and martensite variant distribution was studied using {omega}-scan of selected nuclear Bragg reflections. The neutron diffraction reveals split of the (2 0 0) reflection of major martensite variant and large structural inhomogeneities in martensite phase. Using measurement in reciprocal space, we recorded a set of reflections that appear due to structural modulation (5 M) of the martensite, however, the set seems to be incomplete with missing or very weak reflections of second order compared with X-ray diffraction. The line of the magnetic reflection arising from the supposed antiferromagnetic ordering of the excess Mn atoms was very weak and it is difficult to discern from the background.

  13. Neutron diffraction studies of magnetic-shape memory Ni-Mn-Ga single crystal

    Science.gov (United States)

    Heczko, Oleg; Prokes, Karel; Hannula, Simo-Pekka

    2007-09-01

    Neutron diffraction of single crystal of the typical example of magnetic-shape memory (MSM) alloy Ni 49.7Mn 29.3Ga 21 was carried out with a 2D position sensitive detector. The quality and inhomogeneity of the single crystal and martensite variant distribution was studied using ω-scan of selected nuclear Bragg reflections. The neutron diffraction reveals split of the (2 0 0) reflection of major martensite variant and large structural inhomogeneities in martensite phase. Using measurement in reciprocal space, we recorded a set of reflections that appear due to structural modulation (5 M) of the martensite, however, the set seems to be incomplete with missing or very weak reflections of second order compared with X-ray diffraction. The line of the magnetic reflection arising from the supposed antiferromagnetic ordering of the excess Mn atoms was very weak and it is difficult to discern from the background.

  14. Procedures for interface residual stress determination using neutron diffraction: Mo-coated steel gear wheel

    Science.gov (United States)

    Bruno, Giovanni; Fanara, Carlo; Hughes, Darren J.; Ratel, Nicolas

    2006-05-01

    Residual stresses were determined in steel gear wheels coated with molybdenum using neutron diffraction. A systematic procedure was developed to assess them in both the molybdenum coating and in the steel substrate. A detailed description of the problems associated with measurements of this type is given, together with a procedure aimed at rationalising their solution. Precise sample positioning was developed using a new experimental method and advanced metrology equipment allowing off-line sample alignment and mounting. This reliably replaces the inefficient use of entrance scans, usually adopted in residual stress analysis by neutron diffraction. Corrections were applied to overcome the presence of pseudo-strains and data reduction was performed to coherently interpret the results, including the determination of the centre-of-mass of the diffracting volume. The full three-dimensional stress profile was determined in the coating and the substrate. The data analysis methodology is fully described and recommendations are given for this kind of measurement.

  15. High-resolution neutron powder-diffraction in CMR manganates

    Energy Technology Data Exchange (ETDEWEB)

    Suard, E.; Radaelli, P.G. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Manganese-oxide materials have recently been the subject of renewed attention, due to the `colossal` magnetoresistance (CMR) displayed near the spin-ordering temperature T{sub c} by some of these compounds. CMR has been evidenced in at least three families of manganese oxides. In most cases, the CMR compounds behave as paramagnetic semiconductors at high temperatures, and as ferromagnetic metals below T{sub c}. The study of this metallization process has lead some theorists to challenge its traditional interpretation in terms of the so-called double-exchange mechanism, and to propose alternative scenarios in which the coupling of the charge carriers with the lattice plays a paramount role. Powder diffraction method, being at the forefront of CMR research is presented. (author). 4 refs.

  16. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source.

    Science.gov (United States)

    Mauro, N A; Vogt, A J; Derendorf, K S; Johnson, M L; Rustan, G E; Quirinale, D G; Kreyssig, A; Lokshin, K A; Neuefeind, J C; An, Ke; Wang, Xun-Li; Goldman, A I; Egami, T; Kelton, K F

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (∼100 mg).

  17. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    Science.gov (United States)

    Mauro, N. A.; Vogt, A. J.; Derendorf, K. S.; Johnson, M. L.; Rustan, G. E.; Quirinale, D. G.; Kreyssig, A.; Lokshin, K. A.; Neuefeind, J. C.; An, Ke; Wang, Xun-Li; Goldman, A. I.; Egami, T.; Kelton, K. F.

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (˜100 mg).

  18. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Mauro, N. A., E-mail: namauro@noctrl.edu [Department of Physics, North Central College, Naperville, Illinois 60540 (United States); Vogt, A. J. [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Derendorf, K. S. [Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri 63130 (United States); Johnson, M. L.; Kelton, K. F. [Department of Physics and Institute of Materials Science and Engineering, Washington University, 1 Brookings Drive, St. Louis, Missouri 63130 (United States); Rustan, G. E.; Quirinale, D. G.; Goldman, A. I. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Kreyssig, A. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Division of Materials Sciences and Engineering, Ames Laboratory, Ames, Iowa 50011 (United States); Lokshin, K. A. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Neuefeind, J. C.; An, Ke [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wang, Xun-Li [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Ave., Kowloon (Hong Kong); Egami, T. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Department of Physics and Astronomy, Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2016-01-15

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr{sub 64}Ni{sub 36} measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (∼100 mg)

  19. Neutron applications in materials for energy

    CERN Document Server

    Kearley, Gordon J

    2015-01-01

    Neutron Applications in Materials for Energy collects results and conclusions of recent neutron-based investigations of materials that are important in the development of sustainable energy. Chapters are authored by leading scientists with hands-on experience in the field, providing overviews, recent highlights, and case-studies to illustrate the applicability of one or more neutron-based techniques of analysis. The theme follows energy production, storage, and use, but each chapter, or section, can also be read independently, with basic theory and instrumentation for neutron scattering being

  20. Preliminary time-of-flight neutron diffraction study on diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Marc-Michael [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, D-80937 Munich (Germany); Koglin, Alexander [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115 (United States); Rüterjans, Heinz [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany); Schoenborn, Benno [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Langan, Paul [Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Chemistry, University of Toledo, Toledo, OH 53606 (United States); Chen, Julian C.-H., E-mail: chen@chemie.uni-frankfurt.de [Institute of Biophysical Chemistry, J. W. Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt (Germany)

    2007-01-01

    Diisopropyl fluorophosphatase (DFPase) effectively hydrolyzes a number of organophosphorus nerve agents, including sarin, cyclohexylsarin, soman and tabun. Neutron diffraction data have been collected from DFPase crystals to 2.2 Å resolution in an effort to gain further insight into the mechanism of this enzyme. The enzyme diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris is capable of decontaminating a wide variety of toxic organophosphorus nerve agents. DFPase is structurally related to a number of enzymes, such as the medically important paraoxonase (PON). In order to investigate the reaction mechanism of this phosphotriesterase and to elucidate the protonation state of the active-site residues, large-sized crystals of DFPase have been prepared for neutron diffraction studies. Available H atoms have been exchanged through vapour diffusion against D{sub 2}O-containing mother liquor in the capillary. A neutron data set has been collected to 2.2 Å resolution on a relatively small (0.43 mm{sup 3}) crystal at the spallation source in Los Alamos. The sample size and asymmetric unit requirements for the feasibility of neutron diffraction studies are summarized.

  1. The Laue diffraction method to search for a neutron EDM. Experimental test of the sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Fedorov, V.V. E-mail: vfedorov@mail.pnpi.spb.ru; Lapin, E.G.; Lelievre-Berna, E.; Nesvizhevsky, V.V.; Petoukhov, A.K.; Semenikhin, S.Yu.; Soldner, T.; Tasset, F.; Voronin, V.V

    2005-01-01

    The feasibility of an experiment to search for the neutron electric dipole moment (EDM) by Laue diffraction in crystals without a center of symmetry was tested. At the PF1A beam of the ILL reactor a record time delay of {tau}{approx}2 ms for the passage of neutrons through a quartz crystal was reached for the (1 1 0) plane and diffraction angles equal to 88.5 degrees. That corresponds to an effective neutron velocity in the crystal of 20 m/s, while the velocity of the incident neutron was 800 m/s. It was shown experimentally that the value {tau}N{sup 1/2}, determining the method's sensitivity, has a maximum for the Bragg angle equal to 86 deg. The results allow us to estimate the statistical sensitivity of the method for the neutron EDM. For the PF1B beam of the ILL reactor the sensitivity can reach {approx}6x10{sup -25} e cm per day for the available quartz crystal.

  2. BOOK REVIEW: Analysis of Residual Stress by Diffraction Using Neutron and Synchrotron Radiation

    Science.gov (United States)

    Fitzpatrick, ed M. E.; Lodini, A.

    2003-09-01

    The presence of residual stresses within engineering components is often a key feature in determining their usable lifetimes and failure characteristics. Residual surface compression can, for example, restrict the propagation of surface cracks through the bulk. As a consequence, it is essential to characterize the magnitude and spatial distribution of residual stresses and, at least for non-destructive testing, this is most widely achieved using diffraction of neutron and high energy synchrotron radiations. This book aims to provide a detailed description of the methodology used to determine residual stresses. The major emphasis is placed on the neutron method, this being the more widely established approach at present. It contains 20 chapters contributed by 23 authors, divided into five major parts. The overall layout is very logical, with the first part giving a general introduction to the use of neutrons and x-rays for materials research and summarizing the methods used for their production. Part 2 considers the more specific aspects of extracting the residual stress distribution within a bulk sample and includes some valuable comments on a number of potential experimental problems, such as the determination of the stress-free lattice parameter and the effects of broadening of the Bragg peaks. The experimental facilities currently available or under development are described in part 3, with the remaining two parts devoted to general and specific applications of the residual stress measurement technique. As expected with such a large number of different authors, there is some variation in style and quality. However, the text is generally easy to follow and, more importantly, it is largely free of the problems of inconsistent notation and dupication of material that can afflict multi-authored texts. My only negative comment concerns the latter portion of the book devoted to specific applications of the technique, which is illustrative rather than comprehensive. In

  3. On the reliability of neutron diffraction for residual stress measurement in cold-drawn steels

    Science.gov (United States)

    Ruiz-Hervias, J.; Mompean, F.; Hofmann, M.; Atienza, J. M.

    2011-10-01

    Residual strains were measured in the ferrite phase of pearlitic steel rods along the radial, axial and hoop directions. Two samples with different initial diameters were subjected to one drawing pass (using same drawing parameters) with 20% section reduction and measured in two different neutron diffraction instruments. The results show that the residual strain state is very similar in both cases, regardless of the diameter of the initial rod. This means that the final residual strain-stress state is unique and it is related to the cold-drawing process parameters. In addition, the results show the reliability of strain scanning with different neutron instruments and experimental conditions.

  4. Neutron Powder Diffraction Study on Structure of LaNi3.8AlMn0.2 Compound

    Institute of Scientific and Technical Information of China (English)

    HAN; Wen-ze; GUO; Hao; SUN; Kai; CHEN; De-min; LIU; Shi; WU; Er-dong; LIU; Yun-tao; CHEN; Dong-feng

    2015-01-01

    The structures of original LaNi3.8AlMn0.2alloy and subsequent compounds by means of annealing at different temperatures(850,900,950,1 000℃)were examined by using neutron diffraction and X-ray diffraction,as shown in Figure 1.Based on the Rietveld method,the diffraction

  5. A 3D profile function suitable for integration of neutron time-of-flight single crystal diffraction peaks

    Science.gov (United States)

    Gutmann, Matthias J.

    2017-03-01

    A 3D profile function is presented suitable to integrate reflections arising in time-of-flight (TOF) single crystal neutron diffraction experiments. In order to account for the large asymmetry of the peak shape in the TOF direction, a 3D Gaussian ellipsoid in the pixel (x, z) and time-of-flight coordinates is convoluted with a rising and falling exponential along the time-of-flight direction. An analytic expression is derived, making it suitable for least-squares fitting. The application of this function in detector space or reciprocal space is straightforward.

  6. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, D.J., E-mail: d.hughes@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Koukovini-Platia, E. [CERN, CH-1211 Geneva 23 (Switzerland); Heeley, E.L. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2014-02-15

    Highlights: • Residual stresses were determined in a welded EUROFER blanket assembly with integrated cooling channels. • Good agreement was seen between experimentally determined and predicted stresses. • We show that microstructure changes that occur in EUROFER steels during welding must be considered for residual stress determination. • An experimental route is proposed for validation of predicted stresses in reactor components using non-destructive diffraction techniques. - Abstract: Whilst the structural integrity and lifetime considerations in welded joints for blanket modules can be predicted using finite element software, it is essential to prove the validity of these simulations. This paper provides detailed analysis for the first time, of the residual stress state in a laser-welded sample with integral cooling channels. State-of-the-art non-destructive neutron diffraction was employed to determine the triaxial stress state and to understand microstructural changes around the heat affected zone. Synchrotron X-ray diffraction was used to probe the variation of strain-free lattice reference parameter around the weld zone allowing correction of the neutron measurements. This paper details an important experimental route to validation of predicted stresses in complex safety-critical reactor components for future applications.

  7. Stress-induced martensite variant reorientation in magnetic shape memory Ni Mn Ga single crystal studied by neutron diffraction

    Science.gov (United States)

    Molnar, P.; Sittner, P.; Lukas, P.; Hannula, S.-P.; Heczko, O.

    2008-06-01

    Stress-induced martensite variant reorientation in magnetic shape memory Ni-Mn-Ga single crystal was studied in situ by the neutron diffraction technique. Principles of determination of individual tetragonal martensitic variants in shape memory alloys are explained. Using neutron diffraction we show that the macroscopic strain originates solely from the martensite structure reorientation or variant redistribution. Neutron diffraction also reveals that the reorientation of martensite is not fully completed even at a stress value of 25 MPa, which is about 20 times larger than the mean stress needed for reorientation. Only one twinning system is active during the reorientation process.

  8. Lithium plating in lithium-ion batteries investigated by voltage relaxation and in situ neutron diffraction

    Science.gov (United States)

    von Lüders, Christian; Zinth, Veronika; Erhard, Simon V.; Osswald, Patrick J.; Hofmann, Michael; Gilles, Ralph; Jossen, Andreas

    2017-02-01

    In this work, lithium plating is investigated by means of voltage relaxation and in situ neutron diffraction in commercial lithium-ion batteries. We can directly correlate the voltage curve after the lithium plating with the ongoing phase transformation from LiC12 to LiC6 according to the neutron diffraction data during the relaxation. Above a threshold current of C/2 at a temperature of -2 °C, lithium plating increases dramatically. The results indicate that the intercalation rate of deposited lithium seems to be constant, independent of the deposited amount. It can be observed that the amount of plating correlates with the charging rate, whereas a charging current of C/2 leads to a deposited amount of lithium of 5.5% of the charge capacity and a current of 1C to 9.0%.

  9. Neutron powder diffraction and theory-aided structure refinement of rubidium and cesium ureate

    Energy Technology Data Exchange (ETDEWEB)

    Sterri, Kjersti B.; Deringer, Volker L.; Houben, Andreas; Jacobs, Philipp [RWTH Aachen Univ. (Germany). Inst. of Inorganic Chemistry; Kumar, Chogondahalli M.N. [Forschungszentrum Juelich GmbH, Juelich Centre for Neutron Science (JCNS), Outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Oak Ridge National Laboratory, TN (United States). Chemical and Engineering Materials Div.; Dronskowski, Richard [RWTH Aachen Univ. (Germany). Inst. of Inorganic Chemistry; RWTH Aachen Univ. (Germany). Juelich-Aachen Research Alliance (JARA-HPC)

    2016-08-01

    Urea (CN{sub 2}H{sub 4}O) is a fundamental biomolecule whose derivatives are abundant throughout chemistry. Among the latter, rubidium ureate (RbCN{sub 2}H{sub 3}O) and its cesium analog (CsCN{sub 2}H{sub 3}O) have been described only very recently and form the first structurally characterized salts of deprotonated urea. Here, we report on a neutron diffraction study on the aforementioned alkaline-metal ureates, which affords the positions for all hydrogen atoms (including full anisotropic displacement tensors) and thus allows us to gain fundamental insights into the hydrogen-bonding networks in the title compounds. The structure refinements of the experimental neutron data proceeded successfully using starting parameters from ab initio simulations of atomic positions and anisotropic displacement parameters. Such joint experimental-theoretical refinement procedures promise significant practical potential in cases where complex solids (organic, organometallic, framework materials) are studied by powder diffraction.

  10. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

    DEFF Research Database (Denmark)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A.

    2017-01-01

    constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND......-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure...... enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time...

  11. A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

    Science.gov (United States)

    O'Neill, Brian; Tenailleau, Christophe; Nogthai, Yung; Studer, Andrew; Brugger, Joël; Pring, Allan

    2006-11-01

    A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25-300 °C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni) 9S 8 to violarite (Fe,Ni) 3S 4 under mild conditions (pH∼4) at 120 °C and 3 bar using in situ neutron diffraction measurements are presented.

  12. Neutron diffraction measurements and modeling of residual strains in metal matrix composites

    Science.gov (United States)

    Saigal, A.; Leisk, G. G.; Hubbard, C. R.; Misture, S. T.; Wang, X. L.

    1996-01-01

    Neutron diffraction measurements at room temperature are used to characterize the residual strains in tungsten fiber-reinforced copper matrix, tungsten fiber-reinforced Kanthal matrix, and diamond particulate-reinforced copper matrix composites. Results of finite element modeling are compared with the neutron diffraction data. In tungsten/Kanthal composites, the fibers are in compression, the matrix is in tension, and the thermal residual strains are a strong function of the volume fraction of fibers. In copper matrix composites, the matrix is in tension and the stresses are independent of the volume fraction of tungsten fibers or diamond particles and the assumed stress free temperature because of the low yield strength of the matrix phase.

  13. Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding

    CERN Document Server

    Fiori, F

    2002-01-01

    Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (ten...

  14. Neutron diffraction on CeMnAlD{sub x} (0{<=}x{<=}2.5)

    Energy Technology Data Exchange (ETDEWEB)

    Spatz, P.; Gross, K.; Schlapbach, L. [Fribourg Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    CeMnAl was found to absorb considerable amounts of hydrogen. Part of the totally stored hydrogen is absorbed at low pressures (< 10 mbar). Additional hydrogen can be absorbed and desorbed reversible in a wide pressure range (10 mbar to 10 bar) at room temperature. In order to a better understanding of this new metal-hydride system, we performed neutron diffraction on deuterated CeMnAl samples with different D-concentrations. (author) 1 fig., 2 refs.

  15. Neutron diffraction analysis of residual stresses near unannealed welds in anhydrous ammonia nurse tanks.

    Science.gov (United States)

    Becker, A T; Chumbley, L S; Goettee, D; Russell, A M

    2014-01-01

    Neutron diffraction analysis was employed to measure residual stresses near welds in used anhydrous ammonia nurse tanks. Tensile residual stresses contribute to stress corrosion cracking of nurse tanks, which can cause tanks to release toxic ammonia vapor. The analysis showed that tensile residual stresses were present in the tanks measured, and the magnitudes of these stresses approached the yield strength of the steel. Implications for agricultural safety and health are discussed.

  16. Secondary Extinction in Cylindrical and Spherical Crystals for X-Ray and Neutron Diffraction

    Institute of Scientific and Technical Information of China (English)

    胡华琛; 李兆桓; 杨斌; 沈彩万; 乔英

    2001-01-01

    The distribution of the reflection power ratio for a neutron or x-ray diffracted from a cylindrical crystal immersed in an homogenous incident beam is obtained by the numerical solution of the transfer equations for the first time. The profile well reflects all the physical properties of the absorption and extinction behaviour in the crystals. A systematic investigation of the secondary extinction for cylindrical and spherical crystals was carried out based on these results.

  17. Residual strain scanning of alumina-based ceramic composites by neutron diffraction

    Science.gov (United States)

    Ruiz-Hervias, J.; Bruno, G.; Bueno, S.; Gurauskis, J.; Baudín, C.; Fan, K. Y.

    2014-11-01

    Residual strain profiles were measured by neutron diffraction in alumina-aluminum titanate ceramic composites sintered at two different temperatures, namely 1450 and 1550°C. The results show that irrespective of the direction and the sintering temperature, the obtained profiles are almost flat, with very similar results for both temperatures. In addition, the results demonstrate that the alumina is in compression whereas the aluminium titanate is subjected to tensile residual stresses.

  18. Neutron Diffraction Study of Magnetic Ordering in Cd1-xMnxTe

    DEFF Research Database (Denmark)

    Giebultowicz, T.; Kepa, H.; Buras, B.;

    1981-01-01

    Neutron diffraction experiments were performed on Cd1−xMnxTe crystals for x=0.40, 0.60, 0.63, 0.65 and 0.70. Magnetic Bragg scattering was observed at low temperatures for xgreater-or-equal, slanted0.60 corresponding to the Type III antiferromagnetic ordering of a f.c.c. sub-lattice. The Néel tem...... temperatures decreasing with x were determined and the critical concentration xc was estimated....

  19. The catalytic mechanism of an aspartic proteinase explored with neutron and X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kovalevsky, Andrey [Los Alamos National Laboratory (LANL); Erskine, Peter T. [University of Southampton, England; Cooper, Jon [University of Southampton, England

    2008-01-01

    Hydrogen atoms play key roles in enzyme mechanism, but as this study shows, even high-quality X-ray data to a resolution of 1 {angstrom} cannot directly visualize them. Neutron diffraction, however, can locate deuterium atoms even at resolutions around 2 {angstrom}. Both neutron and X-ray diffraction data have been used to investigate the transition state of the aspartic proteinase endothiapepsin. The different techniques reveal a different part of the story, revealing the clearest picture yet of the catalytic mechanism by which the enzyme operates. Room temperature neutron and X-ray diffraction data were used in a newly developed joint refinement software package to visualize deuterium atoms within the active site of the enzyme when a gem-diol transition state analogue inhibitor is bound at the active site. These data were also used to estimate their individual occupancy, while analysis of the differences between the bond lengths of the catalytic aspartates was performed using atomic resolution X-ray data. The two methods are in agreement on the protonation state of the active site with a transition state analogue inhibitor bound confirming the catalytic mechanism at which the enzyme operates.

  20. A prompt gamma neutron activation analysis facility using a diffracted beam

    Science.gov (United States)

    Harling, Otto K.; Chabeuf, Jean-Michel; Lambert, Frédérique; Yasuda, Gopika

    1993-12-01

    A prompt gamma neutron activation analysis facility has been constructed at the MIT Research Reactor using a diffracted beam from a multilayered graphite monochromator. A beam of 0.0143 eV neutrons of intensity 6 × 10 6{n}/{cm 2}s is available at the sample position. Backgrounds are low due to the use of the diffracted beam and are further improved by a sapphire crystal in the beam line. This design allowed the Ge detecting crystal to be placed close to the sample position, 4 cm, with a resultant high detection efficiency. The sensitivity of the facility is reported for several representative pure elements. The major impetus for the construction of this facility was the need for accurate analyses of 10B in biological samples for neutron capture therapy research. Detailed results for this type of analysis are provided. The sensitivity of this diffracted beam facility currently exceeds that of two representative direct beam facilities using reactors of twice the power of the MITR-II. Possible major improvements in sensitivity, more than an order of magnitude, and in background levels are outlined for future development.

  1. Neutron diffraction and quasielastic neutron scattering studies of films of intermediate-length alkanes adsorbed on a graphite surface

    Science.gov (United States)

    Diama, Armand

    Over the past several years, we have conducted a variety of elastic neutron diffraction and quasielastic neutron scattering experiments to study the structure and the dynamics of films of two intermediate-length alkane molecules (C nH2n+2), adsorbed on a graphite basal-plane surface. The two molecules are the normal alkane n-tetracosane [n-CH 3(CH2)22CH3] and the branched alkane squalane (C30H62 or 2, 6, 10, 15, 19, 23-hexamethyltetracosane) whose carbon backbone is the same length as teteracosane. The temperature dependence of the monolayer structure of tetracosane and squalane was investigated using elastic neutron diffraction and evidence of two phase transitions was observed. Both the low-coverage tetracosane (C 24H50) and squalane (C30H62) monolayers have crystalline-to-"smectic" and "smectic"-to-isotropic fluid phase transitions upon heating. The diffusive motion in the tetracosane and squalane monolayers has been investigated by quasielastic neutron scattering. Two different quasielastic neutron scattering spectrometers at the Center for Neutron Research, National Institute of Standards and Technology (NIST) have been used. The spectrometers differ in both their dynamic range and energy resolution allowing molecular motions to be investigated on time scales in the range 10-13--10 -9 s. On these time scales, we observe evidence of translational, rotational, and intermolecular diffusive motions in the tetracosane and squalane monolayers. We conclude that the molecular diffusive motion in the two monolayers is qualitatively similar. Thus, despite the three methyl sidegroups at each end of the squalane molecule, its monolayer structure, phase transitions, and dynamics are qualitatively similar to that of a monolayer of the unbranched tetracosane molecules. With the higher resolution spectrometer at NIST, we have also investigated the molecular diffusive motion in multilayer tetracosane films. The analysis of our measurements indicates slower diffusive motion in

  2. An improved prompt gamma neutron activation analysis facility using a focused diffracted neutron beam

    Science.gov (United States)

    Riley, Kent J.; Harling, Otto K.

    1998-09-01

    The performance of the prompt gamma neutron activation analysis (PGNAA) facility at the MIT Research Reactor has been improved by a series of modifications. These modifications have increased the flux by a factor of three at the sample position to 1.7 × 10 7 n/cm 2 s, and have increased the sensitivity, on average, by a factor of 2.5. The background for many samples of interest is dominated by unavoidable neutron interactions that occur in or near the sample. Other background components comprise only 20% of the total background count rate. The implementation of fast electronics has helped to keep dead time reasonable, in spite of the increased count rates. The PGNAA facility at the MIT Research Reactor continues to serve as a major analytical tool for quantifying 10B in biological samples for Boron Neutron Capture Therapy (BNCT) research. The sensitivity for boron-10 in water is 18 750 cps/mg. The sensitivity for pure elements suitable for PGNAA analysis is reported. Possible further improvements are discussed.

  3. Magnetic structures of R(Cu, Ni)2 compounds (R = heavy rare earth) studied by neutron diffraction

    Science.gov (United States)

    Smetana, Z.; Šíma, V.

    1985-11-01

    Magnetics structures of powdered orthorhombic R(Cu, Ni)2 compounds (R = heavy rare earth) determined by neutron diffraction are described. The influence of magnetocrystalline anisotropy and exchange interactions on the type of magnetic ordering is discussed.

  4. Neutron diffraction in a quartz single crystal under the action of acoustic oscillations or a temperature gradient

    CERN Document Server

    Mkrtchyan, A R; Hunanyan, H A; Beglaryan, A G

    1986-01-01

    The paper deals with the problem of neutron diffraction in a quartz single crystal under the action of acoustic oscillations or a temperature gradient in the Laue geometry. Theoretical conclusions were compared with experimental results.

  5. Estimated H-atom anisotropic displacement parameters: a comparison between different methods and with neutron diffraction results

    DEFF Research Database (Denmark)

    Munshi, Parthapratim; Madsen, Anders Ø; Spackman, Mark A;

    2008-01-01

    Anisotropic displacement parameters (ADPs) are compared for H atoms estimated using three recently described procedures, both among themselves and with neutron diffraction results. The results convincingly demonstrate that all methods are capable of giving excellent results for several benchmark...

  6. Analysis of microstress in neutron irradiated polyester fibre by X-ray diffraction technique

    Indian Academy of Sciences (India)

    B Mallick; R C Behera; T Patel

    2005-10-01

    Microstresses developed in the crystallites of polymeric material due to irradiation of high-energy particle causes peak broadening and shifting of X-ray diffraction lines to lower angle. Neutron irradiation significantly changes the material properties by displacement of lattice atoms and the generation of helium and hydrogen by nuclear transmutation. Another important aspect of neutron irradiation is that the fast neutron can produce dense ionization at deep levels in the materials. The polyethylene terephthalate (PET) fibre of raw denier value, 78.2, were irradiated by fast neutron of energy, 4.44 MeV, at different fluences ranging from 1 × 109 n/cm2 to 1 × 1012 n/cm2. In the present work, the radiation heating microstresses developed in PET micro-crystallites was investigated applying X’Pert-MPD Philips Analytical X-ray diffractometer and the effects of microstresses in tensile strength of fibre measured by Instron have also been reported. The shift of 0.45 cm-1 in the Raman peak position of 1614.65 cm-1 to a higher value confirmed the development of microstresses due to neutron irradiation using micro-Raman technique. The defects due to irradiation were observed by SEM micrographs of single fibre for virgin and all irradiated samples.

  7. Disposition of Ceramide in Model Lipid Membranes Determined by Neutron Diffraction

    Science.gov (United States)

    Groen, D.; Gooris, G.S.; Barlow, D.J.; Lawrence, M.J.; van Mechelen, J.B.; Demé, B.; Bouwstra, J.A.

    2011-01-01

    The lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies. In the diffraction pattern, five diffraction orders were observed attributed to a lamellar phase with a repeat distance of 5.4 nm. Using contrast variation, the scattering length density profile could be calculated showing a typical bilayer arrangement. To obtain information on the arrangement of ceramides in the unit cell, a mixture that included a partly deuterated ceramide was also examined. The scattering length density profile of the 5.4-nm phase containing this deuterated ceramide demonstrated a symmetric arrangement of the ceramides with interdigitating acyl chains in the center of the unit cell. PMID:21402030

  8. Disposition of ceramide in model lipid membranes determined by neutron diffraction.

    Science.gov (United States)

    Groen, D; Gooris, G S; Barlow, D J; Lawrence, M J; van Mechelen, J B; Demé, B; Bouwstra, J A

    2011-03-16

    The lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies. In the diffraction pattern, five diffraction orders were observed attributed to a lamellar phase with a repeat distance of 5.4 nm. Using contrast variation, the scattering length density profile could be calculated showing a typical bilayer arrangement. To obtain information on the arrangement of ceramides in the unit cell, a mixture that included a partly deuterated ceramide was also examined. The scattering length density profile of the 5.4-nm phase containing this deuterated ceramide demonstrated a symmetric arrangement of the ceramides with interdigitating acyl chains in the center of the unit cell.

  9. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

    DEFF Research Database (Denmark)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A.

    2017-01-01

    constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND...... enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time....... The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD)....

  10. Advanced sample environments for in situ neutron diffraction studies of nuclear materials

    Science.gov (United States)

    Reiche, Helmut Matthias

    Generation IV nuclear reactor concepts, such as the supercritical-water-cooled nuclear reactor (SCWR), are actively researched internationally. Operating conditions above the critical point of water (374°C, 22.1 MPa) and fuel core temperature that potentially exceed 1850°C put a high demand on the surrounding materials. For their safe application, it is essential to characterize and understand the material properties on an atomic scale such as crystal structure and grain orientation (texture) changes as a function of temperature and stress. This permits the refinement of models predicting the macroscopic behavior of the material. Neutron diffraction is a powerful tool in characterizing such crystallographic properties due to their deep penetration depth into condensed matter. This leads to the ability to study bulk material properties, as opposed to surface effects, and allows for complex sample environments to study e.g. the individual contributions of thermo-mechanical processing steps during manufacturing, operating or accident scenarios. I present three sample environments for in situ neutron diffraction studies that provide such crystallographic information and have been successfully commissioned and integrated into the user program of the High Pressure -- Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron Science Center (LANSCE) user facility. I adapted a sample changer for reliable and fast automated texture measurements of multiple specimens. I built a creep furnace combining a 2700 N load frame with a resistive vanadium furnace, capable of temperatures up to 1000°C, and manipulated by a pair of synchronized rotation stages. This combination allows following deformation and temperature dependent texture and strain evolutions in situ. Utilizing the presented sample changer and creep furnace we studied pressure tubes made of Zr-2.5wt%Nb currently employed in CANDURTM nuclear reactors and proposed for future SCWRs, acting as the primary

  11. Methane storage mechanism in the metal-organic framework Cu3(btc)2: An in situ neutron diffraction study

    NARCIS (Netherlands)

    Getzschmann, J.; Senkovska, I.; Wallacher, D.; Tovar, M.; Fairen-Jimenez, D.; Düren, T.; van Baten, J.M.; Krishna, R.; Kaskel, S.

    2010-01-01

    The adsorption of deutero-methane (CD4) in Cu3(btc)2 (HKUST-1) was investigated at 77 K using high-resolution neutron powder diffraction. Rietveld refinement of the neutron data revealed a sequential filling of the rigid framework at distinct preferred adsorption sites, and showed the importance of

  12. Neutron diffraction study of hydrogen-bond symmetrization in δ-AlOOD

    Science.gov (United States)

    Sano-Furukawa, A.; Hattori, T.; Kuribayashi, T.

    2013-12-01

    δ-AlOOH, a high-pressure polymorph of diaspore, is an important hydrous mineral in the deep earth that has the ability to transport hydrogen into the lower mantle. Theoretical studies have pointed out that hydrogen would locate at the center between two oxygen atoms at high pressure, which is so called hydrogen-bond symmetrization [1]. It was also suggested that the symmetrization would trigger the increase of bulk modulus, which is one of the important parameters of minerals at high pressure. The transition of δ-AlOOH(D) at high pressure has been suggested by X-ray and neutron diffraction [2, 3]. X-ray diffraction study found that the axes a and b where the hydrogen bond is oriented become less compressible above 12 GPa in δ-AlOOD. Neutron diffraction study on δ-AlOOD up to 9.2 GPa showed the increase of O-D bond distance, that is considered as a precousor phenomena of the symmetrization. However, the pressure was insufficient to observe the symmetrization. To investigate the symmetrization of hydrogen bond directly, we conducted neutron diffraction experiments to 16.7 GPa at PLANET, MLF in J-PARC. Powder sample of δ-AlOOD was loaded in Paris-Edinburgh press with double-toroid sintered diamond anvils with methanol-ethanol mixture of pressure medium. In the experiments, the disappearance of 120 refrection was observed at 12.1 GPa, indicating the transition from P21nm to Pnnm, which can be attributed to the disorder of hydrogen bond or the symmtrization. Results of Rietveld refienment will be shown in the presentation. [1] Tsuchiya et al., Geophys. Res. Lett., 29, 1909, 2002. [2] Sano-Furukawa et al., Am. Mineral., 93, 1558-1567, 2008. [3] Sano-Furukawa et al., Am. Mineral., 94, 1255-1261, 2009.

  13. Preliminary neutron diffraction studies of Escherichia coli dihydrofolate reductase bound to the anticancer drug methotrexate

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, Brad C. [University of Tennessee, Knoxville (UTK); Meilleur, Flora [Institut Laue-Langevin (ILL); Myles, Dean A A [ORNL; Howell, Elizabeth E. [University of Tennessee, Knoxville (UTK); Dealwis, Chris G. [University of Tennessee, Knoxville (UTK)

    2005-01-01

    The contribution of H atoms in noncovalent interactions and enzymatic reactions underlies virtually all aspects of biology at the molecular level, yet their 'visualization' is quite difficult. To better understand the catalytic mechanism of Escherichia coli dihydrofolate reductase (ecDHFR), a neutron diffraction study is under way to directly determine the accurate positions of H atoms within its active site. Despite exhaustive investigation of the catalytic mechanism of DHFR, controversy persists over the exact pathway associated with proton donation in reduction of the substrate, dihydrofolate. As the initial step in a proof-of-principle experiment which will identify ligand and residue protonation states as well as precise solvent structures, a neutron diffraction data set has been collected on a 0.3 mm{sup 3} D{sub 2}O-soaked crystal of ecDHFR bound to the anticancer drug methotrexate (MTX) using the LADI instrument at ILL. The completeness in individual resolution shells dropped to below 50% between 3.11 and 3.48 {angstrom} and the I/{sigma}(I) in individual shells dropped to below 2 at around 2.46 {angstrom}. However, reflections with I/{sigma}(I) greater than 2 were observed beyond these limits (as far out as 2.2 {angstrom}). To our knowledge, these crystals possess one of the largest primitive unit cells (P6{sub 1}, a = b = 92, c = 73 {angstrom}) and one of the smallest crystal volumes so far tested successfully with neutrons.

  14. Production, crystallization and neutron diffraction of fully deuterated human myelin peripheral membrane protein P2.

    Science.gov (United States)

    Laulumaa, Saara; Blakeley, Matthew P; Raasakka, Arne; Moulin, Martine; Härtlein, Michael; Kursula, Petri

    2015-11-01

    The molecular details of the formation of the myelin sheath, a multilayered membrane in the nervous system, are to a large extent unknown. P2 is a peripheral membrane protein from peripheral nervous system myelin, which is believed to play a role in this process. X-ray crystallographic studies and complementary experiments have provided information on the structure-function relationships in P2. In this study, a fully deuterated sample of human P2 was produced. Crystals that were large enough for neutron diffraction were grown by a ten-month procedure of feeding, and neutron diffraction data were collected to a resolution of 2.4 Å from a crystal of 0.09 mm(3) in volume. The neutron crystal structure will allow the positions of H atoms in P2 and its fatty-acid ligand to be visualized, as well as shedding light on the fine details of the hydrogen-bonding networks within the P2 ligand-binding cavity.

  15. Crystallization and preliminary neutron diffraction experiment of human farnesyl pyrophosphate synthase complexed with risedronate.

    Science.gov (United States)

    Yokoyama, Takeshi; Ostermann, Andreas; Mizuguchi, Mineyuki; Niimura, Nobuo; Schrader, Tobias E; Tanaka, Ichiro

    2014-04-01

    Nitrogen-containing bisphosphonates (N-BPs), such as risedronate and zoledronate, are currently used as a clinical drug for bone-resorption diseases and are potent inhibitors of farnesyl pyrophosphate synthase (FPPS). X-ray crystallographic analyses of FPPS with N-BPs have revealed that N-BPs bind to FPPS with three magnesium ions and several water molecules. To understand the structural characteristics of N-BPs bound to FPPS, including H atoms and hydration by water, neutron diffraction studies were initiated using BIODIFF at the Heinz Maier-Leibnitz Zentrum (MLZ). FPPS-risedronate complex crystals of approximate dimensions 2.8 × 2.5 × 1.5 mm (∼3.5 mm(3)) were obtained by repeated macro-seeding. Monochromatic neutron diffraction data were collected to 2.4 Å resolution with 98.4% overall completeness. Here, the first successful neutron data collection from FPPS in complex with N-BPs is reported.

  16. Neutron diffraction analysis of residual strain/stress distribution in the vicinity of high strength welds

    Directory of Open Access Journals (Sweden)

    Hamák I.

    2010-06-01

    Full Text Available Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible for defect occurrence during welding and they are also responsible for crack initiation and propagation at the either static or dynamic load. The significant effect of weld metal chemical composition as well as the effect of fatigue load and local plastic deformation on residual stress distribution and fatigue life have been recognized for high strength steels welds. The changes in residual stress distribution have then positive effect on cold cracking behavior and also on fatigue properties of the welds [1-3]. Several experimental methods, both destructive and non-destructive, such as hole drilling method, X-ray diffraction, neutron diffraction and others, have been used to examine residual stress distribution in all three significant orientations in the vicinity of the welds. The present contribution summarizes the results of neutron diffraction measurements of residual stress distribution in the vicinity of single-pass high-strength-steel welds having different chemical composition as well as the influence of fatigue load and local plastic deformation. It has been observed that the chemical composition of the weld metal has a significant influence on the stress distribution around the weld. Similarly, by aplying both cyclic load or pre-stress load on the specimens, stress relaxation was observed even in the region of approximately 40 mm far from the weld toe.

  17. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures.

    Science.gov (United States)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A; Steuwer, Axel; Kiyanagi, Ryoji; Tremsin, Anton S; Knudsen, Erik B; Shinohara, Takenao; Willendrup, Peter K; da Silva Fanta, Alice Bastos; Iyengar, Srinivasan; Larsen, Peter M; Hanashima, Takayasu; Moyoshi, Taketo; Kadletz, Peter M; Krooß, Philipp; Niendorf, Thomas; Sales, Morten; Schmahl, Wolfgang W; Schmidt, Søren

    2017-08-25

    The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure. The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD).

  18. Calorimetric and neutron diffraction studies on transitions of water confined in nanoporous copper rubeanate.

    Science.gov (United States)

    Yamada, Takeshi; Yonamine, Ryo; Yamada, Teppei; Kitagawa, Hiroshi; Yamamuro, Osamu

    2010-07-01

    Copper rubeanate (H(2)C(2)N(2)S(2)Cu) has a nanoporous structure and exhibits high proton conductivity with adsorbing water inside the pores. We have studied the phase behavior and structure of the water confined in copper rubeanate hydrates (H(2)C(2)N(2)S(2)Cu.nH(2)O, n = 0, 2.1, 3.7) by adiabatic calorimetry and neutron powder diffraction. In the hydrate samples, a glass transition and a first-order transition appeared around 150 and 260 K, respectively. The transition entropy was similar to the entropy of fusion of bulk water, indicating that the adsorbed water is disordered above the transition temperature, like bulk water, and ordered below 150 K, like bulk ice. The neutron diffraction data demonstrated that both dry and hydrated copper rubeanates have amorphous structures over the temperature range 100-340 K. The analyses on the diffraction peak owing to the adsorbed water revealed that the transition at 260 K is a liquid-liquid transition due to the condensation of water on the surface of the pores, and the condensed water molecules are gradually ordered below 260 K and frozen-in at the glass transition around 150 K.

  19. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  20. Polarized neutron powder diffraction studies of antiferromagnetic order in bulk and nanoparticle NiO

    DEFF Research Database (Denmark)

    Brok, Erik; Lefmann, Kim; Deen, Pascale P.;

    2015-01-01

    surface contribution to the magnetic anisotropy. Here we explore the potential use of polarized neutron diffraction to reveal the magnetic structure in NiO bulk and nanoparticle powders by applying the XYZ-polarization analysis method. Our investigations address in particular the spin orientation in bulk...... NiO and platelet-shaped NiO nanoparticles with thickness from greater than 200 nm down to 2.0 nm. The advantage of the applied method is that it is able to clearly separate the structural, the magnetic, and the spin-incoherent scattering signals for all particle sizes. For platelet-shaped particles......In many materials it remains a challenge to reveal the nature of magnetic correlations, including antiferromagnetism and spin disorder. Revealing the spin structure in magnetic nanoparticles is further complicated by the large incoherent neutron scattering cross section from water adsorbed...

  1. Determination of the residual stress tensor in textured zirconium alloy by neutron diffraction

    Science.gov (United States)

    Sumin, V. V.; Papushkin, I. V.; Vasin, R. N.; Venter, А. M.; Balagurov, А. М.

    2012-02-01

    Results of neutron diffraction studies of crystallographic texture and residual stress tensor components in cold-worked and annealed cylindrical components made from E-110 zirconium alloy are presented. Those components are used as plugs in the fuel elements of the VVER-type reactors; the resident residual stresses influence the durability and safety of the fuel elements. The experiments were carried out on the neutron diffractometers at Dubna (the IBR-2 pulsed reactor) and Berlin Helmholtz-Zentrum (the BER II research reactor). It is shown that the samples have fiber texture that is changed considerably with annealing. The type I residual stress tensors for both samples were calculated by the BulkPathGEO model. The cold worked component has 136-166 MPa tensile residual stress in the radial direction and zero stress along the axial direction. Residual stress values in the annealed component are close to zero.

  2. Crystallographic and magnetic structures of Pr6Fe13Ge studied by powder neutron diffraction

    Institute of Scientific and Technical Information of China (English)

    Wang Fang-Wei; Zhang Pan-Lin; Shen Bao-Gen; Yan Qi-Wei

    2004-01-01

    Crystallographic and magnetic structures of Pr6Fel3Ge have been investigated by high-resolution powder neutron diffraction in the temperature range of 10-300 K. The magnetic structure consists of ferromagnetic Pr6Fe13 slabs that alternate antiferromagnetically, along c, with the next Pr6Fe13 slab separated by a non-magnetic Ge layer. The magnetic moments lie within the ab-planes. The propagation vector of this structure is k=(001) with respect to the conventional reciprocal lattice of the Ⅰ-centred structure. However, the temperature-dependence of neutron-scattering intensity of the (110) Bragg peak, very similar to the temperature-dependent magnetization measured by SQUID magnetometer,indicates that a small c-axis ferromagnetic component should be added to the above antiferromagnetic model.

  3. Development of procedures for the measurement of residual stress by neutron diffraction

    CERN Document Server

    Webster, G A

    2002-01-01

    Neutron diffraction is a non-destructive method for determining residual stresses in crystalline materials. It is a relatively new technique and no standard is currently available for making these measurements. This paper gives the background to research that has been carried out to develop a standard. It outlines the main findings and indicates the precautions that are required to achieve accurate positioning and alignment of specimens (and components) in a neutron beam and the analysis required to obtain reliable results. It also shows that special attention is needed in dealing with near-surface measurements because of surface aberration. It is demonstrated that, provided the recommended procedures are followed, a positional tolerance of +-0.1 mm can be achieved with an accuracy in strain of propor to 10 sup - sup 4 , to give a resolution in residual stress of propor to 7 to 20 MPa in most materials of practical interest. (orig.)

  4. In situ neutron diffraction studies of a commercial, soft lead zirconate titanate ceramic: response to electric fields and mechanical stress

    Science.gov (United States)

    Pramanick, Abhijit; Prewitt, Anderson D.; Cottrell, Michelle A.; Lee, Wayne; Studer, Andrew J.; An, Ke; Hubbard, Camden R.; Jones, Jacob L.

    2010-06-01

    Structural changes in commercial lead zirconate titanate (PZT) ceramics (EC-65) under the application of electric fields and mechanical stress were measured using neutron diffraction instruments at the Australian Nuclear Science and Technology Organisation (ANSTO) and the Oak Ridge National Laboratory (ORNL). The structural changes during electric-field application were measured on the WOMBAT beamline at ANSTO and include non-180° domain switching, lattice strains and field-induced phase transformations. Using time-resolved data acquisition capabilities, lattice strains were measured under cyclic electric fields at times as short as 30 μs. Structural changes including the (002) and (200) lattice strains and non-180° domain switching were measured during uniaxial mechanical compression on the NRSF2 instrument at ORNL. Contraction of the crystallographic polarization axis, (002), and reorientation of non-180° domains occur at lowest stresses, followed by (200) elastic strains at higher stresses.

  5. Assessment of Shape Memory Alloys - From Atoms To Actuators - Via In Situ Neutron Diffraction

    Science.gov (United States)

    Benafan, Othmane

    2014-01-01

    As shape memory alloys (SMAs) become an established actuator technology, it is important to identify the fundamental mechanisms responsible for their performance by understanding microstructure performance relationships from processing to final form. Yet, microstructural examination of SMAs at stress and temperature is often a challenge since structural changes occur with stress and temperature and microstructures cannot be preserved through quenching or after stress removal, as would be the case for conventional materials. One solution to this dilemma is in situ neutron diffraction, which has been applied to the investigation of SMAs and has offered a unique approach to reveal the fundamental micromechanics and microstructural aspects of bulk SMAs in a non-destructive setting. Through this technique, it is possible to directly correlate the micromechanical responses (e.g., internal residual stresses, lattice strains), microstructural evolutions (e.g., texture, defects) and phase transformation properties (e.g., phase fractions, kinetics) to the macroscopic actuator behavior. In this work, in situ neutron diffraction was systematically employed to evaluate the deformation and transformation behavior of SMAs under typical actuator conditions. Austenite and martensite phases, yield behavior, variant selection and transformation temperatures were characterized for a polycrystalline NiTi (49.9 at. Ni). As the alloy transforms under thermomechanical loading, the measured textures and lattice plane-level variations were directly related to the cyclic actuation-strain characteristics and the dimensional instability (strain ratcheting) commonly observed in this alloy. The effect of training on the shape memory characteristics of the alloy and the development of two-way shape memory effect (TWSME) were also assessed. The final conversion from a material to a useful actuator, typically termed shape setting, was also investigated in situ during constrained heatingcooling and

  6. Magnetization, electrical resistivity, thermopower, and neutron diffraction in HoCu/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Gratz, E. (Technische Univ., Vienna (Austria)); Sechovsky, V.; Sima, V.; Smetana, Z. (Karlova Univ., Prague (Czechoslovakia). Matematicky Ustav); Stroem-Olson, J.O. (McGill Univ., Montreal, Quebec (Canada). Dept. of Physics)

    1982-05-01

    HoCu/sub 2/ shows a Curie-Weiss susceptibility above 15 K. The paramagnetic moment and the paramagnetic Curie temperature is (10.1 +- 0.1) ..mu../sub B//H/sub 0/ and (4 +- 2) K, respectively. Two cusps (at about 7 and 10 K) are seen in the magnetization versus temperature curve. These cusps reflect a change of the magnetic structure and the Neel temperature. The influence of conduction electron scattering on the localized 4f moments is estimated for the resistivity and the thermopower. Neutron diffraction measurements show that the antiferromagnetic structure is incommensurate with the crystal lattice.

  7. Neutron diffraction studies on Ca1-BaZr4P6O24 solid solutions

    Indian Academy of Sciences (India)

    S N Achary; O D Jayakumar; S J Patwe; A B Shinde; P S R Krishna; S K Kulshreshtha; A K Tyagi

    2008-11-01

    Herein we report the results of detailed crystallographic studies of Ca1-BaZr4P6O24 compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from the systematic variation of unit cell parameters. The variation of unit cell parameters with the composition indicates decreasing trend in parameter with increasing Ba2+ concentration contrast to an increasing trend in parameter.

  8. Time-of-flight 3D Neutron Diffraction for Multigrain Crystallography

    DEFF Research Database (Denmark)

    Cereser, Alberto

    detector systems facilitated two versions of ToF 3DND. The first version, restricted to imaging data, enables reconstruction of the position and shape of the individual grains without the use of crystallography. Afterwards, the orientations of the individual grains are indexed. The algorithms for both...... comparison with electron backscatter diffraction (EBSD). In the Iron rod, 107 grains were indexed from the SENJU data. As a comparison, 108 grains were reconstructed from the nearfield data alone. This constitutes roughly 10 times as many grains as previously reported using a continuous neutron source...

  9. Development of a sample environment for neutron diffraction at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Soo; Lee, Chang Hee; Choi, Yong Nam

    2000-06-01

    This report contains the development of low temperature sample environment for the neutron diffraction and its utilization techniques. With this research, a low temperature experimental facility of T=10-300 K was developed. We measured magnetic peak of La{sub 1}.4Sr{sub 1}.6Mn{sub 2}O{sub 7} due to low temperature phase transition successfully by this unit installed at the sample table of HRPD. Therefore, the research capability for various materials under the low temperature was expanded.

  10. Characterizing the dealumination of environmentally relevant zeolites using IR, NMR and neutron diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Paffett, M.T.; Szanyi, J.; Jacubinas, R.M.; Ott, K.C.; VonDreele, R.; Hughes, C.D.; Earl, W.L.

    1997-07-01

    Results of characterization studies monitoring the sequential chemical bond breaking events, local site symmetry, and long range structural modifications of specific zeolites (H-ZSM-5, TS-1) during hydrothermal treatment of these catalyst materials are described. These characterization techniques include infrared spectroscopy of selected probe molecules, magic angle spinning NMR spectroscopy, and powder neutron diffraction. Information regarding selected examples from each of these techniques is presented and the inherent strengths of each is discussed. The experimental insight into the chemical and structural modifications of high surface area microporous catalyst materials as a function of deactivation conditions (hydrothermal conditioning) is highlighted.

  11. On the atomic structure of liquid Ni-Si alloys: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, S; Marczinke, J; Hoyer, W [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Hennet, L [CNRS-CEMHTI, University of Orleans, F-45071 Orleans (France); Cuello, G J, E-mail: sascha.gruner@physik.tu-chemnitz.d [Institute Laue-Langevin, PO Box 156, F-38042 Grenoble (France)

    2009-09-23

    The atomic structure of the liquid NiSi and NiSi{sub 2} alloys is investigated by means of neutron diffraction experiments with isotopic substitution. From experimental data-sets obtained using four Ni isotopes, partial structure factors and pair correlation functions are obtained by applying a reverse Monte Carlo modelling approach. Both alloys were found to exhibit a strong tendency to hetero-coordination within the first coordination shell. In particular, covalent Si-Si bonds with somewhat greater distances seem to influence the structure of the liquid NiSi alloy.

  12. The Crystal Structure of Thorium and Zirconium Dihydrides by X-ray and Neutron Diffraction

    Science.gov (United States)

    Rundle, R.E.; Shull, C.G.; Wollan, E.O.

    1951-04-20

    Thorium forms a tetragonal lower hydride of composition ThH{sub 2}. The hydrides ThH{sub 2}, ThD{sub 2}, and ZrD{sub 2} have been studied by neutron diffraction in order that hydrogen positions could be determined. The hydrides are isomorphous, and have a deformed fluorite structure. Metal-hydrogen distances in thorium hydride are unusually large, as in UH{sub 3}. Thorium and zirconium scattering amplitudes and a revised scattering amplitude for deuterium are reported.

  13. A neutron-diffraction study of the effect of hydration on stratum corneum structure

    Energy Technology Data Exchange (ETDEWEB)

    Charalambopoulou, G.C.; Steriotis, T.A.; Stefanopoulos, K.L.; Stubos, A.K. [NCSR ' Demokritos' , 15310 Agia Paraskevi Attikis (Greece); Hauss, T. [Hahn-Meitner Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

    2002-07-01

    The primary barrier to transdermal diffusion resides in the stratum corneum (SC), the thin outermost layer of the skin. The SC hydration state is one of the most important factors that determine the rate of percutaneous permeability. Despite its great importance, the actual mechanism of water-SC interaction is yet unresolved. In the present work we employ the membrane neutron diffraction method, aiming to reveal structural details of porcine SC and ultimately enable the localization of water molecules in the two phases of the tissue. (orig.)

  14. Neutron diffraction study of multiferroic Mo-doped CoFe2O4

    Science.gov (United States)

    Das, A.; Dwivedi, G. D.; Kumari, Poonam; Shahi, P.; Yang, H. D.; Ghosh, A. K.; Chatterjee, Sandip

    2015-04-01

    Neutron diffraction measurements have been carried out to study the coexistence of magnetic ordering and ferroelectricity at room temperature in CoFe1.8Mo0.2O4. It is observed from this study that the Mo6+ preferentially occupies the octahedral site and it converts some of the Fe3+ ions into Fe2+ ions in the tetrahedral site. The conversion of Fe3+ ions into Fe2+ ions modulate the Fe-Fe distances which in effect induce the ferroelectricity in magnetically ordered CoFe1.8Mo0.2O4.

  15. Neutron powder diffraction studies as a function of temperature of structure II hydrate formed from propane

    Science.gov (United States)

    Rawn, C.J.; Rondinone, A.J.; Chakoumakos, B.C.; Circone, S.; Stern, L.A.; Kirby, S.H.; Ishii, Y.

    2003-01-01

    Neutron powder diffraction data confirm that hydrate samples synthesized with propane crystallize as structure type II hydrate. The structure has been modeled using rigid-body constraints to describe C3H8 molecules located in the eight larger polyhedral cavities of a deuterated host lattice. Data were collected at 12, 40, 100, 130, 160, 190, 220, and 250 K and used to calculate the thermal expansivity from the temperature dependence of the lattice parameters. The data collected allowed for full structural refinement of atomic coordinates and the atomic-displacement parameters.

  16. Molecular conformation and liquid structure of 2-propanol through neutron diffraction

    Indian Academy of Sciences (India)

    A Sahoo; S Sarkar; P S R Krishna; R N Joarder

    2010-05-01

    The neutron diffraction data analysis of deuterated liquid 2-propanol at room temperature to define its molecular conformation is presented. 2-Propanol being a large molecule with twelve atomic sites, the conformation analysis is tricky and an improved method of data analysis is given. The intermolecular structural correlations, i.e., hydrogen-bonded liquid structure, can be modelled accurately to extract the nature of the average hydrogen-bonded molecular association in liquid state at room temperature. Like other alcohols these are mostly hexamer ring chain (HRC) clusters. The cluster analysis of recent X-ray data available in the literature also support the same liquid structure.

  17. Structural behaviour of AgNO3 at low temperatures by neutron diffraction

    Indian Academy of Sciences (India)

    P U Sastry; P S R Krishna; Lata Panicker; A B Shinde

    2008-11-01

    Structural behaviour of silver nitrate (AgNO3) at low temperatures has been investigated by neutron powder diffraction and differential scanning calorimetry (DSC). Analysis showed abnormal changes in the rotations of nitrate (NO3) anions and thermal displacement parameters of the atoms near 220 K and 125 K. However, the basic lattice is compatible with the orthorhombic symmetry (space group Pbca) till 12 K. The fine, small-scale structural anomalies probably originate from freezing of reorientation of NO3 ions from high-temperature disordered phase.

  18. Interrupted Magnetic First Order Transitions and Kinetic Arrest probed with In-field Neutron Diffraction

    Science.gov (United States)

    Siruguri, V.; Kaushik, S. D.; Rayaprol, S.; Babu, P. D.; Chaddah, P.; Sampathkumaran, E. V.; Hoser, A.; Ritter, C.

    2016-09-01

    In-field neutron diffraction studies were carried out on two compounds that exhibit magnetic first order phase transitions (FOPT). It is shown that the FOPT can be interrupted by an external magnetic field, resulting in a coexistence of kinetically arrested metastable states and equilibrium phases. Use of a novel protocol CHUF (Cooling and Heating under Unequal Fields) helps to determine the coexisting phase fractions and also to observe the devitrification of the kinetically arrested phase into the equilibrium phase, in a manner similar to that found in structural glassy systems.

  19. Neutron and X-ray single-crystal diffraction from protein microcrystals via magnetically oriented microcrystal arrays in gels.

    Science.gov (United States)

    Tsukui, Shu; Kimura, Fumiko; Kusaka, Katsuhiro; Baba, Seiki; Mizuno, Nobuhiro; Kimura, Tsunehisa

    2016-07-01

    Protein microcrystals magnetically aligned in D2O hydrogels were subjected to neutron diffraction measurements, and reflections were observed for the first time to a resolution of 3.4 Å from lysozyme microcrystals (∼10 × 10 × 50 µm). This result demonstrated the possibility that magnetically oriented microcrystals consolidated in D2O gels may provide a promising means to obtain single-crystal neutron diffraction from proteins that do not crystallize at the sizes required for neutron diffraction structure determination. In addition, lysozyme microcrystals aligned in H2O hydrogels allowed structure determination at a resolution of 1.76 Å at room temperature by X-ray diffraction. The use of gels has advantages since the microcrystals are measured under hydrated conditions.

  20. Isotope effects in water as investigated by neutron diffraction and path integral molecular dynamics

    Science.gov (United States)

    Zeidler, Anita; Salmon, Philip S.; Fischer, Henry E.; Neuefeind, Jörg C.; Simonson, J. Mike; Markland, Thomas E.

    2012-07-01

    The structures of heavy and light water at 300 K were investigated by using a joint approach in which the method of neutron diffraction with oxygen isotope substitution was complemented by path integral molecular dynamics simulations. The diffraction results, which give intra-molecular O-D and O-H bond distances of 0.985(5) and 0.990(5) Å, were found to be in best agreement with those obtained by using the flexible anharmonic TTM3-F water model. Both techniques show a difference of ≃ 0.5% between the O-D and O-H intra-molecular bond lengths, and the results support a competing quantum effects model for water in which its structural and dynamical properties are governed by an offset between intra-molecular and inter-molecular quantum contributions. Further consideration of the O-O correlations is needed in order to improve agreement with experiment.

  1. Structure of molten TbCl sub 3 measured by neutron diffraction

    CERN Document Server

    Martin, R A; Barnes, A C; Cuello, G J

    2002-01-01

    The total structure factor of molten TbCl sub 3 at 617 deg. C was measured by using neutron diffraction. The data are in agreement with results from previous experimental work but the use of a diffractometer having an extended reciprocal-space measurement window leads to improved resolution in real space. Significant discrepancies with the results obtained from recent molecular dynamics simulations carried out using a polarizable ion model, in which the interaction potentials were optimized to enhance agreement with previous diffraction data, are thereby highlighted. It is hence shown that there is considerable scope for the development of this model for TbCl sub 3 and for other trivalent metal halide systems spanning a wide range of ion size ratios. (letter to the editor)

  2. Neutron Diffraction Study on the Magnetic Structure of Pr6Fe13Sn

    Directory of Open Access Journals (Sweden)

    Suharyana

    2010-04-01

    Full Text Available We have successfully prepared a Pr6Fe13Sn sample by employing argon arc melting. The crystal structure of the sample has been examined by an x-ray diffraction. The x-ray pattern reveals that the sample crystallize in the tetragonal Nd6Fe13Si structure type with space group I4/mcm. Neutron diffraction at 150K performed on a powder sample shows a collinear antiferromagnetic ordering of the Fe and Pr sublattices with the wave vector (0, 0, 1 and an Ip type magnetic lattice with anti-centering translation. The main axis of antiferromagnetism is restricted to the (0 0 1 plane. The average refined Fe moments at 150 K is (2.0±0.4 µB whereas the Pr moments are (2.1±0.4 and (1.9±0.4 µB for the 8f and 16l sites, respectively

  3. X-ray, synchrotron, and neutron diffraction analysis of Roman cavalry parade helmet fragment

    Energy Technology Data Exchange (ETDEWEB)

    Smrcok, L' . [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 84536 Bratislava (Slovakia); Petrik, I. [Geological Institute, Slovak Academy of Sciences, Dubravska cesta 9, 84005 Bratislava (Slovakia); Langer, V. [Environmental Inorganic Chemistry, Chalmers University of Technology, 412 96 Gothenburg (Sweden); Filinchuk, Y. [Swiss-Norwegian Beam Lines, European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP-220, 38043 Grenoble CEDEX (France); Beran, P. [Nuclear Physics Institute ASCR v.v.i. and Research Centre Rez Ltd., 25068 Rez (Czech Republic)

    2010-10-15

    A partially corroded fragment of the neck guard of a Roman cavalry helmet excavated in the former military camp of Gerulata, a part of the Limes Romanus on the River Danube, was analysed by laboratory X-ray, synchrotron and neutron powder diffraction. The approximate phase composition determined by the neutron diffraction of the bulk, 82% (wt) of the copper alloy phase, 12 % (wt) of cuprite and 6% of nantokite indicate a significant degree of corrosion of the artefact. Elemental EDX analysis of cleaned surface showed that the chemical composition of the original alloy is 78 to 82 % (wt) of Cu and 21.4 to 16.5 % of Zn with minute amounts of Sn, Si and S. High contents of Cu and Zn with the negligible amount of Sn showed that the body of the helmet was made of brass and not of bronze as expected before. The amount of zinc in the copper alloy calculated from the refined lattice parameter agrees fairly well with the value determined by EDX. The most abundant phase in the synchrotron powder diffraction pattern of the corrosion products scrapped from the artefact is cuprite, but presence of atacamite, malachite, brochantite, nantokite, mixed Cu-Zn hydroxyl carbonates and probably also of simonkolleite (Zn{sub 5}(OH){sub 8}Cl{sub 2}.H{sub 2}O) have been detected. In contrast, the X-ray pattern taken directly from the surface of the artefact is dominated by atacamite with some traces of malachite and quartz. Because the penetration depth of laboratory X-rays is in order of tens of microns, the phase analysis based only on a diffraction pattern taken from a surface can lead to erroneous conclusions concerning the phase composition of the patina. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Neutron beam applications - Development of one dimensional position sensitive neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Yun; Kang, Hee Dong; Kim, Wan; Moon, Myung Kook [Kyungpook National University, Taegu (Korea)

    2000-04-01

    This research is sponsored and supported by KAERI as a part of {sup D}evelopment of One Dimensional Position Sensitive Neutron Detector{sup .} To apply residual stress measurement and small angle neutron scattering the one dimensional position sensitive neutron detectors which have wide window and good position resolution were designed and fabricated. The detection area are 200 mm x 100, 120 mm x 80 mm. The thermal neutron detection efficiency are about 60%. The spatial resolution of the detector are less than 2mm. The characteristics of the detectors were studied. Using the detector we could get neutron diffraction patterns from some samples. 19 refs., 103 figs., 4 tabs. (Author)

  5. In situ synthesis and characterization of uranium carbide using high temperature neutron diffraction

    Science.gov (United States)

    Reiche, H. Matthias; Vogel, Sven C.; Tang, Ming

    2016-04-01

    We investigated the formation of UCx from UO2+x and graphite in situ using neutron diffraction at high temperatures with particular focus on resolving the conflicting reports on the crystal structure of non-quenchable cubic UC2. The agents were UO2 nanopowder, which closely imitates nano grains observed in spent reactor fuels, and graphite powder. In situ neutron diffraction revealed the onset of the UO2 + 2C → UC + CO2 reaction at 1440 °C, with its completion at 1500 °C. Upon further heating, carbon diffuses into the uranium carbide forming C2 groups at the octahedral sites. This resulting high temperature cubic UC2 phase is similar to the NaCl-type structure as proposed by Bowman et al. Our novel experimental data provide insights into the mechanism and kinetics of formation of UC as well as characteristics of the high temperature cubic UC2 phase which agree with proposed rotational rehybridization found from simulations by Wen et al.

  6. Aging behavior of lithium iron phosphate based 18650-type cells studied by in situ neutron diffraction

    Science.gov (United States)

    Paul, Neelima; Wandt, Johannes; Seidlmayer, Stefan; Schebesta, Sebastian; Mühlbauer, Martin J.; Dolotko, Oleksandr; Gasteiger, Hubert A.; Gilles, Ralph

    2017-03-01

    The aging behavior of commercially produced 18650-type Li-ion cells consisting of a lithium iron phosphate (LFP) based cathode and a graphite anode based on either mesocarbon microbeads (MCMB) or needle coke (NC) is studied by in situ neutron diffraction and standard electrochemical techniques. While the MCMB cells showed an excellent cycle life with only 8% relative capacity loss (i.e., referenced to the capacity after formation) after 4750 cycles and showed no capacity loss on storage for two years, the needle coke cells suffered a 23% relative capacity loss after cycling and a 11% loss after storage. Based on a combination of neutron diffraction and electrochemical characterization, it is shown that the entire capacity loss for both cell types is dominated by the loss of active lithium; no other aging mechanisms like structural degradation of anode or cathode active materials or deactivation of active material could be found, highlighting the high structural stability of the active material and the excellent quality of the investigated cells.

  7. The chemical reactivity and structure of collagen studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wess, T.J.; Wess, L.; Miller, A. [Univ. of Stirling (United Kingdom)

    1994-12-31

    The chemical reactivity of collagen can be studied using neutron diffraction (a non-destructive technique), for certain reaction types. Collagen contains a number of lysine and hydroxylysine side chains that can react with aldehydes and ketones, or these side chains can themselves be converted to aldehydes by lysyl oxidase. The reactivity of these groups not only has an important role in the maintenance of mechanical strength in collagen fibrils, but can also manifest pathologically in the cases of aging, diabetes (reactivity with a variety of sugars) and alcoholism (reactivity with acetaldehyde). The reactivity of reducing groups with collagen can be studied by neutron diffraction, since the crosslink formed in the adduction process is initially of a Schiff base or keto-imine nature. The nature of this crosslink allows it to be deuterated, and the position of this relatively heavy scattering atom can be used in a process of phase determination by multiple isomorphous replacement. This process was used to study the following: the position of natural crosslinks in collagen; the position of adducts in tendon from diabetic rats in vivo and the in vitro position of acetaidehyde adducts in tendon.

  8. Structure and dynamics of aqueous 2-propanol: a THz-TDS, NMR and neutron diffraction study.

    Science.gov (United States)

    McGregor, James; Li, Ruoyu; Zeitler, J Axel; D'Agostino, Carmine; Collins, James H P; Mantle, Mick D; Manyar, Haresh; Holbrey, John D; Falkowska, Marta; Youngs, Tristan G A; Hardacre, Christopher; Stitt, E Hugh; Gladden, Lynn F

    2015-11-11

    Aqueous liquid mixtures, in particular, those involving amphiphilic species, play an important role in many physical, chemical and biological processes. Of particular interest are alcohol/water mixtures; however, the structural dynamics of such systems are still not fully understood. Herein, a combination of terahertz time-domain spectroscopy (THz-TDS) and NMR relaxation time analysis has been applied to investigate 2-propanol/water mixtures across the entire composition range; while neutron diffraction studies have been carried out at two specific concentrations. Excellent agreement is seen between the techniques with a maximum in both the relative absorption coefficient and the activation energy to molecular motion occurring at ∼90 mol% H2O. Furthermore, this is the same value at which well-established excess thermodynamic functions exhibit a maximum/minimum. Additionally, both neutron diffraction and THz-TDS have been used to provide estimates of the size of the hydration shell around 2-propanol in solution. Both methods determine that between 4 and 5 H2O molecules per 2-propanol are found in the 2-propanol/water clusters at 90 mol% H2O. Based on the acquired data, a description of the structure of 2-propanol/water across the composition range is presented.

  9. Magnetic Structure of Goethite α-FeOOH: A Neutron Diffraction Study

    Science.gov (United States)

    Zepeda-Alarcon, E.; Nakotte, H.; Vogel, S. C.; Wenk, H.

    2013-12-01

    Goethite (α-FeOOH) is found in diverse natural ecosystems, it is by far the most common oxyhydroxide in terrestrial soils, sediments and clays and an important mineral in the biogeochemical cycle of iron at the Earth's surface. Neutron diffraction studies have found that the iron magnetic moments are collinear in a two sublattice antiferromagnetic structure, aligned parallel to the c axis in space group Pbnm (Forsyth et. al. 1968). However, goethite shows superparamagnetic behavior and also a weak ferromagnetic component that has been attributed to the presence of lattice distortions. It is thought that these changes in magnetic ordering could be due to a 13° canting of the magnetic moment with respect to the c-axis, which enables the flipping of the spins due to small perturbations in the lattice (Coey et. al. 1995). In this study we used neutron diffraction at HIPPO and NPDF beamlines at LANSCE of Los Alamos National Laboratory on a powder of natural goethite provided by A. Gualtieri. The nuclear and magnetic structures were determined by means of a Rietveld refinement with GSAS and it was found that the spins of the iron atoms are aligned parallel to the c-axis, with no evidence of spin canting. The net magnetic moment is lower than what has previously been found. These results provide further insight into the magnetic ordering of this mineral and can be important in understanding the physical processes responsible for goethite's intriguing magnetic behavior.

  10. Complex investigation of deformation twinning in γ-TiAl by TEM and neutron diffraction

    Science.gov (United States)

    Beran, Premysl; Heczko, Milan; Kruml, Tomas; Panzner, Tobias; van Petegem, Steven

    2016-10-01

    A near-γ TiAl based alloy with 2 at% of Nb was investigated by means of collaborative research based on transmission electron microscopy and in-situ neutron diffraction techniques with the aim to study mechanical twinning and its role within the mechanisms governing fatigue response and material properties. In-situ neutron diffraction measurements were performed during low cycle fatigue straining at room temperature. Induced lattice strain related to the formation of deformation twins was detected and used to follow changes in the macroscopic material response caused by the twinning process during cycling. A microscopic insight was realised by using several transmission electron microscopy techniques to reveal in detail an internal deformation microstructure of the material at the beginning as well as at the end of the fatigue life. The study was focused on the first loading cycles where the material shows intense cyclic hardening. The effect of mechanical twinning on the material behaviour at several stages of the fatigue life is discussed for two different total strain amplitudes of 0.2% and 0.4%.

  11. Crystal and magnetic structures of Cr1/3NbSe2 from neutron diffraction

    Science.gov (United States)

    Gubkin, A. F.; Proskurina, E. P.; Kousaka, Y.; Sherokalova, E. M.; Selezneva, N. V.; Miao, P.; Lee, S.; Zhang, J.; Ishikawa, Y.; Torii, S.; Kamiyama, T.; Campo, J.; Akimitsu, J.; Baranov, N. V.

    2016-01-01

    Neutron diffraction measurements of the Cr intercalated niobium diselenide Cr1/3NbSe2 together with magnetization measurements have revealed that this compound exhibits ferromagnetic ordering below TC = 96 K unlike a chiral helimagnetic order observed in the sulfide compound Cr1/3NbS2. As derived from neutron diffraction data, the Cr magnetic moments μCr = 2.83 ± 0.03 μB in Cr1/3NbSe2 are aligned within basal plane. The discrepancy in the magnetic states of Cr1/3NbS2 and Cr1/3NbSe2 is ascribed to the difference in the preferential site occupation of Cr ions in crystal lattices. In Cr1/3NbSe2, the Cr ions are predominantly distributed over 2b Wyckoff site, which determines a centrosymmetric character of the crystal structure unlike Cr1/3NbS2, where the Cr ions are mainly located in 2c position and the crystal structure is non-centrosymmetric.

  12. Neutron diffraction study of Heusler type alloy Mnsub(0. 47)Vsub(0. 28)Alsub(0. 25)

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Hiroshi; Nakamichi, Takuro; Yamaguchi, Yasuo; Kazama, Noriaki

    1983-05-01

    Crystal and magnetic structures of an annealed Mn-V-Al ternary alloy were investigated by powder neutron diffraction. Neutron diffraction measurements confirmed clearly that the Mn-V-Al alloy specimen with approximate composition Mn/sub 2/ VAl annealed at 1023 K for 48 h has the Heusler (L2/sub 1/)-type structure. Our studies on the annealed alloy specimen, Mnsub(1.88) Vsub(1.12) Alsub(1.00), showed that Mn atom occupies preferentially the simple cubic Mn sublattice ..cap alpha..(A + C), while V and Al atoms occupy the B and D sublattices, respectively, in the bcc structure composed of four equivalent fcc sublattices A, B, C and D. It was suggested strongly that Mn atom has the magnetic moment (1.5 +- 0.3)..mu.. sub(B) in the sublattice ..cap alpha.. and couples antiferromagnetically with V atom which has the magnetic moment 0.9..mu.. sub(B) in the B sublattice.

  13. Using Neutron Diffraction to Determine the Low-Temperature Behavior of Pb2+ in Lead Feldspar

    Science.gov (United States)

    Kolbus, L. M.; Anovitz, L. M.; Chakoumackos, B. C.; Wesolowski, D. J.

    2014-12-01

    Feldspar minerals comprise 60% of the Earth's crust, so it imperative that the properties of feldspar be well understood for seismic modeling. The structure of feldspar consists of a three-dimensional framework of strongly-bonded TO4 tetrahedra formed by the sharing of oxygen atoms between tetrahedra. The main solid solution series found in natural feldspars are alkali NaAlSi3O8 -KAlSi3O8 and plagioclase CaAl2Si2O8-NaAlSi3O8. Recently, efforts have been made to systematically quantify feldspars structural change at non-ambient temperatures by considering only the relative tilts of the tetrahedral framework [1]. This serves as a tool to predict various behaviors of the structure such as the relative anisotropy of unit cell parameters and volume evolution with composition and temperature. Monoclinic feldspars are well predicted by the model [1], but discrepancies still remain between the model predictions and real structures with respect to absolute values of the unit cell parameters. To improve the existing model, a modification must be made to account for the M-cation interaction with its surrounding oxygen atoms. We have, therefore, chosen to study the structure of Pb-feldspar (PbAl2Si2O8), which provides the opportunity to characterize a monoclinic Al2Si2 feldspar containing a large M-site divalent cation using neutron diffraction. Neutron diffraction allows for the characterization of the M-site cation interaction between the oxygen atoms in the polyhedral cage by providing information to accurately determine the atomic displacement parameters.. Lead feldspar was synthesized for this study using the method described in [2], and confirmed to have a monoclinic C2/m space group. In this talk we will present structural determinations and atomic displacement parameters of Pb-feldspar from 10 - 300K generated from Neutron diffraction at the POWGEN beamline at the Spallation Neutron Source at Oak Ridge National lab, and compare our results to those predicted by the

  14. Probing the Hydrogen Sublattice of FeHx with High-Pressure Neutron Diffraction

    Science.gov (United States)

    Murphy, C. A.; Guthrie, M.; Boehler, R.; Somayazulu, M.; Fei, Y.; Molaison, J.; dos Santos, A. M.

    2013-12-01

    The combination of seismic, cosmochemical, and mineral physics observations have revealed that Earth's iron-rich core must contain some light elements, such as hydrogen, carbon, oxygen, silicon, and/or sulfur. Therefore, understanding the influence of these light elements on the structural, thermoelastic, and electronic properties of iron is important for constraining the composition of this remote layer of the Earth and, in turn, providing constraints on planetary differentiation and core formation models. The high-pressure structural and magnetic properties of iron hydride (FeHx) have previously been studied using synchrotron x-ray diffraction and Mössbauer spectroscopy. Such experiments revealed that the double hexagonal close-packed (dhcp) structure of FeHx is stable above a pressure of ~5 GPa and up to at least 80 GPa at 300 K [1]. In addition, dhcp-FeHx is ferromagnetic at low-pressures, but undergoes a magnetic collapse around 22 GPa [2]. X-ray experiments provide valuable insight into the properties of FeHx, but such techniques are largely sensitive to the iron component because it is difficult to detect the hydrogen sublattice with x-rays. Therefore, neutron diffraction has been used to investigate metastable FeHx, which is formed by quenching the high-pressure phase to liquid nitrogen temperatures and probing the sample at ambient pressure [3]. However, such neutron experiments have been limited to formation pressures below 10 GPa, and cannot be performed at ambient temperature. Here we present the first in-situ investigation of FeHx at 300 K using high-pressure neutron diffraction experiments performed at the Spallation Neutrons and Pressure Diffractometer (SNAP) instrument at the Spallation Neutron Source, Oak Ridge National Laboratory. In order to achieve pressures of ~50 GPa, we loaded iron samples with a hydrogen gas pressure medium into newly designed large-volume panoramic diamond-anvil cells (DACs) for neutron diffraction experiments [4; 5]. We

  15. GENERALIZED FRESNEL DIFFRACTION INTEGRAL AND ITS APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    YANG JUN; FAN DIAN-YUAN; WANG SHI-JI; GU YUAN

    2000-01-01

    Within the generalized definition of ABCDGH matrices, the conventional ABCDGH diffraction integral is ex-tended for a misaligned complex paraxial system with a curved optical axis. On this basis the transformation lawfor Gaussian-Schell model beams through an ABCDGH systems is derived, the propagation behavior of the mutualcoherence function through ABCDGH systems in the presence of random media is investigated as well.

  16. Single-crystal neutron diffraction on γ-LiAlO{sub 2}. Structure determination and estimation of lithium diffusion pathway

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Dennis; Lerch, Martin [Technische Univ. Berlin (Germany). Inst. fuer Chemie; Indris, Sylvio; Heitjans, Paul [Hannover Univ. (Germany). Inst. fuer Physikalische Chemie und Elektrochemie and ZFM; Meven, Martin [RWTH Aachen (Germany). Inst. fuer Kristallographie; Juelich Centre for Neutron Scattering (JCNS), Garching (Germany). Heinz Maier-Leibnitz Zentrum (ZLM); Pedersen, Bjoern [Technische Univ. Muenchen, Garching (Germany). Heinz Maier-Leibnitz Zentrum (MLZ); Boysen, Hans [Muenchen Univ. (Germany). Sektion Kristallographie; Uecker, Reinhard [Leibniz-Institut fuer Kristallzuechtung, Berlin (Germany)

    2016-05-01

    γ-Lithium aluminum oxide is a paradigmatic example of an ultraslow lithium ion conductor. This characteristic plays a crucial role in its proposed and actual applications. Herein, we report on the outcome of single-crystal neutron diffraction studies at ambient and high temperature. Careful evaluation confirms the commonly assumed room-temperature structure as derived by powder neutron diffraction in 1965. At 1043 K, a split of the lithium position hints at the onset of intrinsic diffusion. Analysis of the negative scattering-length density using the maximum-entropy method (MEM) indicates a preference for a strongly curved diffusion pathway traversing octahedral voids between adjacent lithium sites. These results help to understand ultraslow lithium diffusion in well-ordered ionic solids on the microscopic scale and, ultimately, to establish structure-property relationships.

  17. Effect of external stress on deuteride (hydride) precipitation in Zircaloy-4 using in situ neutron diffraction

    Science.gov (United States)

    Lin, Jun-li; An, Ke; Stoica, Alexandru D.; Heuser, Brent J.

    2017-04-01

    In situ neutron diffraction is utilized to study the deuteride (hydride) precipitation behavior in a cold-worked stress-relieved (CWSR) Zircaloy-4 material upon cooling from 420 °C to room temperature with a 78 MPa external stress applied along the rolling direction (RD) of the material. Two banks detector capture the diffraction signal from two principal directions of the specimen, the normal direction (ND) and the rolling direction (RD). The evolution of deuterium concentration in zirconium solid solution along the two specimen directions is measured by studying the δ-(220) peak intensity, applying the Rietveld refinement method to the diffraction data and using the measured zirconium c-axis lattice distortion. The deuterium concentration is observed to be higher for zirconium grains in the ND than the RD. The terminal solid solubility of precipitation (TSSp) for deuterium in the solution is then described using the Arrhenius equation. It is observed that the applied stress reduces the energy term Q in the Arrhenius equation when compared with the unstressed Q values from the work of others. A model by Puls is applied to study the effect of stress on deuterium solubility, with polycrystalline hydride precipitation strain calculated using the Kearns factor representative of the studied material. The experimental result does not agree with the model prediction of Puls.

  18. Evaluation of residual stresses in composite materials by using neutron diffraction; study of elasto-plasticity; Etude des composites a matrice metallique par la technique de la diffraction de neutrons: analyse du comportement elastoplastique et evaluation des contraintes residuelles

    Energy Technology Data Exchange (ETDEWEB)

    Levy-Tubiana, R

    1999-11-05

    This work deals with the study of Metal Matrix Composites (MMC) using neutrons diffraction method and the analysis of the elastoplastic behavior in such materials. First, we evaluated macro-stresses in aluminium MMC reinforced with 17%vol. of SiC particles. One of the analyzed sample has been 4 point bending deformed, measurements have been performed after relaxation. The difference between the coefficients of thermal expansion constrains the matrix to be in tensile state and the particles in compressive state in the sample which has not be deformed. In the sample deformed, the MMC response is predicted by the science of Resistance Materials applied to a bent bar. We assume that macro-stresses are the sum of stresses with different origins (elastic, plastic, thermal mismatch): elastic mismatch is evaluated by Eshelby model and we determined micro-stresses in the unbent bar: they are equivalent and constant along width direction. For the bent bar, we observe relaxation of thermal stresses in the surface region. Theses results are confirmed by measurements of tensile/compressive sample using neutrons diffraction method. We also observed the influence of mechanical and thermal treatment on such MMC: the shear stress (established by the auto-coherent model) depends only on the way of cooling. Finally, a study was performed on titanium MMC for SNECMA on rotor beings used in the gas turbine engine industry. Evolution of stresses between felloe and boring is confirmed by a finite elements modeling and they are the first experimental results in this application. (author)

  19. Structural studies of lithium zinc borohydride by neutron powder diffraction, Raman and NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ravnsbaek, D.B. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Frommen, C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Reed, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Filinchuk, Y. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Institute of Condensed Matter and Nanosciences, Universite Catholique de Louvain, 1 Place L. Pasteur, B-1348, Louvain-la-Neuve (Belgium); Sorby, M.; Hauback, B.C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Jakobsen, H.J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Book, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Besenbacher, F. [Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Skibsted, J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Jensen, T.R., E-mail: trj@chem.au.dk [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark)

    2011-09-15

    Research highlights: > Structural study of the first interpenetrated framework hydride, LiZn{sub 2}(BH{sub 4}){sub 5} > Determination of deuterium positions and revision of crystal structure by PND. > Raman spectroscopy confirms the presence of isolated [Zn{sub 2}(BD{sub 4}){sub 5}]-bar complex anions. > Determination of quadrupole coupling parameters and chemical shifts by {sup 11}B MAS NMR. - Abstract: The crystal structure of LiZn{sub 2}(BH{sub 4}){sub 5} is studied in detail using a combination of powder neutron diffraction (PND), Raman spectroscopy, and {sup 11}B MAS NMR spectroscopy on LiZn{sub 2}(BH{sub 4}){sub 5} and LiZn{sub 2}({sup 11}BD{sub 4}){sub 5}. The aim is to obtain detailed structural knowledge of the first interpenetrated framework hydride compound, LiZn{sub 2}(BD{sub 4}){sub 5} which consists of doubly interpenetrated 3D frameworks built from dinuclear complex ions [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} and lithium ions. The positions of the deuterium atoms are determined using Rietveld refinement of the PND data and the orientation of one of the four independent BD{sub 4}{sup -} groups is revised. The current data reveal that the structure of [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} is more regular than previously reported, as are also the coordinations around the Zn and Li atoms. Both Zn and Li atoms are found to coordinate to the BD{sub 4}{sup -} units via the tetrahedral edges. Some distortion of the angles within the BD{sub 4} units is observed, relative to the expected angles of 109.4 for the ideal tetrahedral coordination. Raman spectroscopy confirms bending and stretching modes from the expected terminal and bridging bidentate BH{sub 4}{sup -} and BD{sub 4}{sup -} units. The {sup 11}B MAS NMR spectrum of the satellite transitions resolves two distinct manifolds of spinning sidebands, which allows estimation of the {sup 11}B quadrupole coupling parameters and isotropic chemical shifts for the four distinct {sup 11}B sites of [Zn{sub 2}(BD

  20. The structure of liquid semiconductors, superionic conductors and glasses by neutron scattering, X-ray diffraction and extended X-ray absorption fine structure

    CERN Document Server

    Buchanan, P

    2001-01-01

    NDIS technique alone. The structure of liquid FeTe sub 2 was determined at the total structure factor level using neutron diffraction in order to estimate the effect of chalcogenide ion size on the structure. The results demonstrate the feasibility of the additional structural determination techniques for disordered materials made possible through the development of third generation X-ray synchrotron sources. A study of the applicability of modern X-ray and neutron scattering techniques to the study of the structure of liquid semiconductors and glasses has been made. The results demonstrate how neutron scattering with isotopic substitution (NDIS), anomalous X-ray scattering and Extended X-ray Absorption Fine Structure (EXAFS) can be successfully used to elucidate the structure of materials that cannot be studied by NDIS alone. The local coordination structure of Ag sub 2 Se in its room temperature, superionic and liquid phases has been determined using the EXAFS technique. This EXAFS data have been combined w...

  1. In Situ Neutron Diffraction Study of NiTi-21Pt High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Benafan, O.; Gaydosh, D. J.; Noebe, R. D.; Qiu, S.; Vaidyanathan, R.

    2016-12-01

    In situ neutron diffraction was used to investigate the microstructural features of stoichiometric and Ti-rich NiTiPt high-temperature shape memory alloys with target compositions of Ni29Ti50Pt21 and Ni28.5Ti50.5Pt21 (in atomic percent), respectively. The alloys' isothermal and thermomechanical properties (i.e., moduli, thermal expansion, transformation strains, and dimensional stability) were correlated to the lattice strains, volume-averaged elastic moduli, and textures as determined by neutron diffraction. In addition, the unique aspects of this technique when applied to martensitic transformations in shape memory alloys are highlighted throughout the paper.

  2. Structural and theoretical investigations of short hydrogen bonds: neutron diffraction and plane-wave DFT calculations of urea phosphoric acid

    Science.gov (United States)

    Wilson, Chick C.; Morrison, Carole A.

    2002-08-01

    Low temperature neutron diffraction and high level computational methods have been applied to investigate the short hydrogen bond in urea-phosphoric acid. It is found that isolated molecule calculations predict a `normal' O-H⋯O hydrogen bond, in strong disagreement with the very short, 3 c-4 e hydrogen bond found from the neutron diffraction. Extending these calculations into a periodic environment using plane-wave DFT methods give much improved agreement with experiment, with a much shorter, stronger hydrogen bond, and significant elongation of the O-H `covalent' bond.

  3. Low-temperature neutron diffraction study of La0.95Nd0.05CrO3

    Indian Academy of Sciences (India)

    Keka R Chakraborty; S M Yusuf; P S R Krishna; M Ramanadham; A K Tyagi

    2004-08-01

    We have synthesized polycrystalline La0.95Nd0.05CrO3 sample by doping the La-site of LaCrO3 with Nd and its magnetic properties have been studied using DC magnetization and neutron diffraction techniques. DC magnetization study shows a paramagnetic to a weak ferromagnetic-like transition at ∼295 K followed by signatures of a spin reorientation phenomenon at 233 and 166 K and, finally a transition to an antiferromagnetic like phase at ∼ 21 K. Low-temperature neutron diffraction measurements confirm a weak ferrimagnetic ordering of Cr3+ moments at all temperatures below 295 K.

  4. Neutron and X-ray diffraction study of residual and internal stress evolution in pearlitic steel during cold drawing

    Science.gov (United States)

    Kriška, M.; Tacq, J.; Van Acker, K.; Seefeldt, M.; Van Petegem, S.

    2012-02-01

    Neutron and X-ray diffraction were used to study the residual and internal stress evolution during cold drawing in pearlitic steel wires. A selection of high strength filaments drawn to different reductions has been investigated. In order to compare the evolution of macro and micro residual phase stresses in ferrite, the lattice strain evolution has been studied in axial and transverse direction. In-situ neutron diffraction tests in "Poisson" geometry have been carried out at the TOF strain scanner POLDI at PSI, Switzerland. These tests revealed a significant scatter in mechanical response among differently oriented ferrite grains, including a peculiar response of the {200} reflection, cp. [1, 2].

  5. Compared FEM and neutron diffraction study of residual strains in Eurofer97 prototype laser welds for fusion reactor technology

    Energy Technology Data Exchange (ETDEWEB)

    Coppol, R. [ENEA - Casaccia, FPN, CP Roma (Italy); Asserin, O. [CEA Saclay, 91 - Gif sur Yvette (France); Hughes, D.J. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)

    2007-07-01

    Full text of publication follows: A reliable characterization of residual strains and stresses is a crucial step in the development of high quality welds for Helium-Cooled-Lithium-Lead (HCLL) blanket modules for DEMO. This contribution will present the first results of a comparative study, carried out using Finite Element Model (FEM) calculations and neutron diffraction measurements to determine the strain and stress field in an Eurofer97 (9Cr, 0.01C, 1W, 0.2V Fe bal wt%) prototype laser weld. The neutron diffraction measurements were carried out at the SALSA diffractometer at the High Flux Reactor of the Institut Max von Laue-Paul Langevin, Grenoble, France. A diffracting volume of approximately 1 x 1 x 5 mm{sup 3} was defined, giving appropriate neutron counting times and allowing a significant comparison with the material volume sampled by FEM. The measurements were carried out at various distances from the weld and within the Heat Affected Zone (HAZ), where the analysis of the detected diffraction line-widths provides information on the metallurgic phases produced during the heat treatment. The neutron diffraction results are compared with the theoretical calculations in view of providing them with an experimental validation. (authors)

  6. Neutron diffraction study of the magnetic structure of HoCu 2

    Science.gov (United States)

    Smetana, Z.; Šíma, V.; Lebech, B.

    1986-05-01

    Neutron diffraction measurements show that in the temperature range from 7.4 to TN=10.4 K the magnetic structure of HoCu 2 is a commensurably modulated a-axis collinear structure with a wave vector q1=1/3 a∗. Below 7.4 K an additional structure component develops and the low temperature magnetic structure of HoCu 2 is found to be an incommensurably modulated non-collinear structure characterized by wave vectors q 1=/13; a∗, q2= qcc∗ and 2 q2, where a∗ and c∗ are reciprocal lattice vectors of the orthorhombic structure and qc=0.300±0.005. The corresponding moment components μ- q1, μq2 and μ2q2 lie along the a, b and b directions of the orthorhombic crystal lattice, respectively.

  7. Magnetic structure study of antiferromagnet NpPtGa{sub 5} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Jonen, S. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan)], E-mail: jonen.shintaro@jaea.go.jp; Metoki, N. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Yamamoto, E. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Homma, Y.; Aoki, D. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Shiokawa, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2008-01-10

    The magnetic structure of NpPtGa{sub 5}was investigated by neutron diffraction. NpPtGa{sub 5} exhibits an A-type antiferromagnetic structure with propagation vector q{sup {yields}}=(0,0,1/2) below T{sub N}=26 K. The estimated Np magnetic moment is 0.38(5) {mu}{sub B}, and it is oriented parallel to the <100> direction. This small moment would be consistent with the large {gamma}=123 mJ/(K{sup 2} mol), indicative of the heavy fermion nature. The field-induced anomaly in the magnetic susceptibility is clarified to be a signature for an antiferromagnetic domain change between multi-domains to single-domain states.

  8. Magnetic structure of Pr6Fe13Ge studied by Mossbauer effect and neutron diffraction

    Institute of Scientific and Technical Information of China (English)

    王芳卫; 张泮霖; 严启伟; 宫华扬

    2000-01-01

    Magnetic structure of Pr6Fe13Ge at room temperature has been investigated by magnetic measurement, Mossbauer effect and neutron diffraction. Magnetic atoms are closely packed up and down the mirror planes at z = 0 and 1/2 and separated by the non-magnetic atoms located on the planes at z= 1/4 and 3/4, which constructs an M/NM/M sandwich structure (M: magnetic, NM: non-magnetic). The intralayer magnetic moments couple ferromagnetically and are out of ab plane at a small angle so as to form a component along c-axis. The interlayer coupling is antiferromagnetic for the ab component while ferromagnetic for the c component.

  9. Neutron diffraction study of NaNO{sub 2} ferroelectric nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, S.; Hansen, T.; Kumzerov, Yu.; Naberezhnov, A.; Simkin, V.; Smirnov, O.; Sotnikov, A.; Tovar, M.; Vakhrushev, S

    2004-07-15

    For the first time the temperature evolution of the structure of ferroelectric nanowires of NaNO{sub 2} was studied by neutron diffraction from room temperature up to melting, i.e. in ferro- and paraelectric phases. Samples were produced in natural chrysotile asbestos with average channel diameter 6{+-}1.5 nm. It is demonstrated that in the ferroelectric phase the structure is consistent with the bulk but is strongly textured. The temperature dependence of order parameter in the ferroelectric phase is determined for the confined sodium nitrite. It is shown that this dependence follows a power law with T{sub c}=413.0{+-}2.5 K and {beta}=0.34{+-}0.05, and differs from the same for the bulk material.

  10. Degradation analysis of 18650-type lithium-ion cells by operando neutron diffraction

    Science.gov (United States)

    Shiotani, Shinya; Naka, Takahiro; Morishima, Makoto; Yonemura, Masao; Kamiyama, Takashi; Ishikawa, Yoshihisa; Ukyo, Yoshio; Uchimoto, Yoshiharu; Ogumi, Zempachi

    2016-09-01

    In-situ and operando neutron diffraction are used to analyze the degradation of 18650-type Li-ion cells. Structural characterization of the electrode materials is performed by applying the Rietveld refinement technique to the in-situ data. The structural refinement of both electrodes in the degraded cells indicates that the amount of active Li-ions is reduced by 14.4% and 13.7% in the cathode and anode, respectively. This reduction is good in agreement with the capacity loss determined electrochemically. The results suggest that capacity loss might be mainly caused by loss of active Li-ions due to side reactions such as solid electrolyte interface (SEI) growth. Furthermore, operando measurements are performed to examine the deterioration of the electrode and active materials. Because the structural evolution depending on capacity is increased in the cathode of degraded cells, it is presumed that the cathode active material has deteriorated due to phase transitions.

  11. Residual stresses in LENS[reg] components using neutron diffraction and contour method

    Energy Technology Data Exchange (ETDEWEB)

    Rangaswamy, P. [Los Alamos National Laboratory, Materials Science and Technology, Los Alamos, NM 87545 (United States)]. E-mail: partha@lanl.gov; Griffith, M.L. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Prime, M.B. [Los Alamos National Laboratory, Materials Science and Technology, Los Alamos, NM 87545 (United States); Holden, T.M. [Los Alamos National Laboratory, Materials Science and Technology, Los Alamos, NM 87545 (United States); Rogge, R.B. [National Research Council of Canada, Chalk River Laboratories Chalk River, Ont., K0J 1J0 (Canada); Edwards, J.M. [Los Alamos National Laboratory, Materials Science and Technology, Los Alamos, NM 87545 (United States); Sebring, R.J. [Los Alamos National Laboratory, Materials Science and Technology, Los Alamos, NM 87545 (United States)

    2005-06-15

    During manufacturing of components by laser engineered net shaping (LENS[reg]), a solid freeform fabrication process, the introduction of residual stresses causes deformation or in the worst case, cracking. The origin is attributed to thermal transients encountered during solidification. In the absence of reliable predictive models for the residual stresses, measurements are necessary. Residual stresses were measured in LENS[reg] samples of 316 stainless steel and Inconel 718 having simple geometrical shapes by both neutron diffraction and the contour methods. The results by the two methods are compared and discussed in the context of the growth direction during the LENS[reg] process. Surprisingly, the residual stresses are practically uni-axial, with high stresses in the growth direction.

  12. In-situ neutron diffraction measurement of stress redistribution in a dissimilar joint during heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Dodge, M.F., E-mail: michael.dodge@twi.co.uk [TWI Ltd., Great Abington, Cambridge CB21 6AL (United Kingdom); Gittos, M.F. [TWI Ltd., Great Abington, Cambridge CB21 6AL (United Kingdom); Dong, H. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Zhang, S.Y.; Kabra, S.; Kelleher, J.F. [ISIS, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2015-03-11

    Neutron diffraction is routinely used to monitor stress redistribution before and after heat treatment in dissimilar joints. However there remains a paucity of information concerning the evolution of strain throughout the process of heat treatment itself. Due to different mechanical properties between opposing sides, a competitive strain redistribution process occurs. Consequently, a novel in-situ measurement approach has been developed: strains at multiple points in a dissimilar joint have been measured during heat treatment. Thus, the described work elucidates areas within the thermal cycle in which competitive strain redistribution occurs, and where high residual stresses remain, following PWHT. The method may be used to characterise comparable material combinations, with a view to optimising the thermal cycles, and ultimately, the structural integrity of dissimilar joints.

  13. Neutron diffraction study of U-5.4 wt% Mo alloy

    Science.gov (United States)

    Lee, Jeong-Soo; Lee, Chang-Hee; Kim, Ki Hwan; Em, Vyacheslav

    2000-06-01

    The structure of U-5.4 wt% Mo alloy prepared by the centrifugal atomization method and the decomposition of the alloy at elevated temperature were studied. The single uniform γ-phase was obtained after annealing the synthesized alloy at 700°C for 48 h. The homogenized alloy was annealed at 400°C and 500°C to search for an ordered phase and study the decomposition process. No ordered phase in U-5.4 wt% Mo alloy after annealing was observed. With the result from the Rietveld refinement of the neutron diffraction patterns it was concluded that the b parameter of the α-phase is contracted like metastable α'-phase and phase boundary of the α-phase region at 500°C lies near 2.6 at.% Mo.

  14. Thiourea-doped ammonium dihydrogen phosphate: A single crystal neutron diffraction investigation

    Indian Academy of Sciences (India)

    A Jayarama; M R Suresh Kumar; S M Dharmaprakash; R Chitra; R R Choudhury

    2008-11-01

    Thiourea-doped ammonium dihydrogen phosphate (TADP) exhibits nonlinear optical property and the second harmonic generation efficiency of these crystals is three times that of pure ammonium dihydrogen phosphate (ADP) crystal. In this context, the study of structural distortion in the thiourea-doped ADP crystal is significant, hence single neutron diffraction investigations were undertaken. The final -factors are: [2 > 2(2)] = 0.11, Goodness of fit () = 1.15. Though the dopant could not be located from the difference Fourier map, the cell parameters ( = = 7.531(3) Å, = 7.544(5) Å) were found to be significantly greater than that of pure ADP at RT ( = = 7.502(1)$ ̊Å, = 7.546(1) Å). This indicates that the dopant concentration in the crystals is small but enough to bring changes in the overall average structure.

  15. Neutron diffraction measurements for the determination of residual stresses in MMC tensile and fatigue specimens

    DEFF Research Database (Denmark)

    Fiori, F.; Girardin, E.; Giuliani, A.;

    2000-01-01

    , residual stresses are present in both the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, having a strong influence on the mechanical behaviour of MMCs. Neutron diffraction measurements...... have been performed at RISO (Roskilde, DK) and HMI-BENSC (Berlin, D), for the determination of residual stress in AA2124 + 17% SiCp and AA359 + 20% SiCp specimens, submitted to tensile and fatigue tests. For each of the investigated samples, the macrostress has been separated from the elastic...... and thermal mismatch microstresses. The results show that, in general, the main contribution to the stress state of both matrix and reinforcement is given by the thermal microstresses, already existing due to heat treatment prior to mechanical tests. (C) 2000 Elsevier Science B.V. All rights reserved....

  16. Structural studies of Li{sub 3}N using neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Huq, Ashfia [Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, IL 60439 (United States)]. E-mail: ahuq@anl.gov; Richardson, James W. [Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Maxey, Evan R. [Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Chandra, Dhanesh [Metallurgical and Materials Engineering, University of Nevada, Reno, Reno, NV 89557 (United States); Chien, Wen-Ming [Metallurgical and Materials Engineering, University of Nevada, Reno, Reno, NV 89557 (United States)

    2007-06-14

    The search for alternative fuel has spurred interest in complexes with high hydrogen absorption-desorption capacities. Among these compounds complex metal hydrides have received much attention. More recently, it was proposed that simple metal nitrides such as lithium nitride (Li{sub 3}N), with its 9 wt% recyclable hydrogen uptake, could be good candidates for reversible hydrogen storage. In this paper, we present the results of detailed structural study of Li{sub 3}N through the temperature range 20-673 K using neutron powder diffraction. Commercially purchased compound showed a co-existence of alpha and beta phases of Li{sub 3}N. We observed a steady decline of the beta phase above 473 K and a very small fraction ({approx}2.5 wt%) remained untransformed at 673 K. This transformation (beta to alpha) was not reversible on cooling.

  17. Hydration and hydrolysis of samarium (III) in montmorillonite clay: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, O; Charlet, L; Gehin, A; Geoffroy, N [LGIT-OSUG, University of Grenoble I and CNRS, BP 53, F-38041 Grenoble Cedex 9 (France); Cuello, G J [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble Cedex 9 (France); Brendle, J [LMPC, UMR CNRS 7016, ENSCMu, UHA, 3 rue A Werner, 68093 Mulhouse Cedex (France)

    2008-03-12

    Neutron diffraction with isotopic substitution was carried out at room temperature on hydrated samples of Sm montmorillonite, prepared at pH = 4 and 8, in order to find out whether Sm is present as aqueous Sm(OH){sub 3}{sup o}, Sm{sup 3+}, or intermediate hydrolyzed species, and how it is linked to the clay surface. It was found that the number of hydrogen atoms (5.5 {+-} 2.0) nearest to Sm{sup 3+} at pH = 4 is equal to or even slightly smaller than that of oxygen atoms (7.5 {+-} 1.0). This means that Sm{sup 3+} is bound to the clay surface and it is probably partially hydrolyzed. This result is very close to those obtained earlier for Yb{sup 3+} and Nd{sup 3+}, despite the different methods of sample preparation and the different mineralogy of the samples.

  18. Neutron diffraction structure determination of NaAlD{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hauback, B.C.; Brinks, H.W.; Jensen, C.M.; Murphy, K.; Maeland, A.J

    2003-08-25

    The structure of NaAlD{sub 4} has been determined from Rietveld-type refinements of powder neutron diffraction data at 8 and 295 K. The space group is I4{sub 1}/a with a=501.19(1) and c=1131.47(5) pm at 295 K. The Na atoms are surrounded by eight D atoms from eight different [AlD{sub 4}]{sup -} tetrahedra in the geometry of a distorted square antiprism. The two different Na-D distances are nearly equal: 240.3(2) and 240.5(2) pm at 8 K and 243.1(2) and 243.9(2) pm at 295 K. The Al-D distance is 162.7(2) and 162.6(2) pm at 8 and 295 K, respectively.

  19. Neutron diffraction studies of the low-temperature magnetic structure of hexagonal FeGe

    DEFF Research Database (Denmark)

    Bernhard, J.; Lebech, Bente; Beckman, O.

    1984-01-01

    The magnetic structure of the hexagonal polymorph of FeGe has been investigated by means of neutron diffraction on single crystals at low temperature and for magnetic fields applied perpendicular to the c axis. Between 410 and approximately 55K the magnetic structure is collinear c......-axis antiferromagnetic. Below approximately 55K the structure changes to c-axis double-cone antiferromagnetic with an inter-layer turn angle for the basal-plane moment component of 194.4 degrees , independent of temperature and applied field. The cone half-angle increases with decreasing temperature to approximately 14...... degrees at 4.2K, but its temperature dependence shows a pronounced kink at 30K, indicating a phase change at this temperature. At 4.2K the authors observe an anomalous decrease of the basal-plane moment component at a critical field (B perpendicular to c) of 1.4 T. As the temperature is increased...

  20. Complex magnetic ordering in CeFe1.76 studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Jayasekara, Wageesha T [Ames Laboratory; Tian, W [Oak Ridge National Laboratory; Hodovanets, Halyna [Ames Laboratory; Canfield, Paul C [Ames Laboratory; Bud' ko, Serguei L [Ames Laboratory; Kreyssig, Andreas [Ames Laboratory; Goldman, Alan I [Ames Laboratory

    2014-10-01

    Neutron diffraction measurements on a single crystal of CeGe1.76 reveal a complex series of magnetic transitions at low temperature. At TN≈7 K, there is a transition from a paramagnetic state at higher temperature to an incommensurate magnetic structure characterized by a magnetic propagation vector (0 0 τ) with τ≈1/4 and the magnetic moment along the a axis of the orthorhombic unit cell. Below TLI≈5 K, the magnetic structure locks in to a commensurate structure with τ=1/4 and the magnetic moment remains along the a axis. Below T≈4 K, we find additional half-integer and integer indexed magnetic Bragg peaks consistent with a second commensurately ordered antiferromagnetic state.

  1. Residual stress measurements via neutron diffraction of additive manufactured stainless steel 17-4 PH.

    Science.gov (United States)

    Masoomi, Mohammad; Shamsaei, Nima; Winholtz, Robert A; Milner, Justin L; Gnäupel-Herold, Thomas; Elwany, Alaa; Mahmoudi, Mohamad; Thompson, Scott M

    2017-08-01

    Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS) 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF). Of these specimens, two were rods (diameter=8 mm, length=80 mm) built vertically upward and one a parallelepiped (8×80×9 mm(3)) built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V).

  2. Residual stress measurements via neutron diffraction of additive manufactured stainless steel 17-4 PH

    Directory of Open Access Journals (Sweden)

    Mohammad Masoomi

    2017-08-01

    Full Text Available Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF. Of these specimens, two were rods (diameter=8 mm, length=80 mm built vertically upward and one a parallelepiped (8×80×9 mm3 built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V.

  3. Magnetization distribution in paramagnetic CoO: a polarized neutron diffraction study

    CERN Document Server

    Kernavanois, N; Brown, P J; Henry, J Y; Lelievre-Berna, E

    2003-01-01

    Unpolarized and polarized neutron diffraction by a single crystal have been used to study the magnetization distribution in the paramagnetic phase of cobalt oxide CoO. Highly accurate magnetic structure factors have been measured using the classical polarized beam method. A detailed description of the magnetization distribution is presented. The magnetization around the cobalt site has a radial distribution which is contracted by approx = 5% with respect to that of the free ion and a symmetry which approximates more closely to e sub g than to the form t sub 2 sub g sup 5 /e sub g sup 2 expected for the Co sup 2 sup + 3d sup 7 configuration. A significant magnetization, corresponding to some 8% of the total moment, is found at the oxygen site.

  4. Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

    CERN Document Server

    Rogge, R B; Boyce, D

    2002-01-01

    Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxia...

  5. Texture Evolution and Phase Transformation in Titanium Investigated by In-Situ Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dong [ORNL; Stoica, Alexandru Dan [ORNL; An, Ke [ORNL; Yang, Ling [ORNL; Bei, Hongbin [ORNL; Mills, Rebecca A [ORNL; Skorpenske, Harley David [ORNL; Wang, Xun-Li [ORNL

    2011-01-01

    We report in-situ neutron diffraction studies of texture evolution and the (hcp) (bcc) phase transformation in commercially pure cold-drawn titanium upon continuous heating and cooling, complemented by differential scanning calorimetry (DSC) measurements. We show that the recrystallization of the phase at elevated temperature enhanced the preexisting fiber texture, which eventually facilitated the nucleation and growth of the phase favored by the Burgers orientation relationship, i.e., {0001} //{110} . More strikingly, upon completion of the transformation, the {110} texture (or preferred orientation) in was eliminated immediately by the rapid grain growth of intergranular allotriomorphs. This resulted in the loss of the original -texture when Ti was transformed back to from to upon subsequent cooling, distinct from the known texture memory effect for rolling textures in titanium. Our present work provides useful experimental results for understanding the mechanisms of texture evolution and phase transformation in titanium and its alloys and, by and large, low-symmetry alloys such as zirconium.

  6. Neutron diffraction study of multipole order in light rare-earth hexaborides

    Indian Academy of Sciences (India)

    J-M Mignat; J Robert; M Sera; F Iga

    2008-10-01

    Multipole interactions are known to play a central role in the unconventional properties of light rare-earth hexaborides and especially of CeB6. Substituting Pr at the Ce sites has the effect of enhancing exchange interactions and changing the symmetry of the local 4f charge distribution, while suppressing the octupole moment. The (,) magnetic phase diagrams of the CePr1-B6 compounds display a large variety of ordered phases involving magnetic and/or charge degrees of freedom. Here we focus on the compound Ce0.7Pr0:3B6, which is located slightly beyond the Pr concentration where the antiferroquadrupolar phase of pure CeB6 is suppressed in zero field. The different magnetic structures have been characterized by neutron diffraction and their origin is discussed in connection with recent non-resonant X-ray results by Tanaka et al.

  7. Neutron diffraction study of Li4Ti5O12 at low temperatures

    Science.gov (United States)

    Dolotko, Oleksandr; Senyshyn, Anatoliy; Mühlbauer, Martin J.; Boysen, Hans; Monchak, Mykhailo; Ehrenberg, Helmut

    2014-10-01

    The crystal structure of the "zero-strain" positive electrode material Li4Ti5O12 was characterized by neutron powder diffraction in the temperature range 3.4 K-300 K. No phase transition was detected, and the thermal evolution of lattice parameters has been evaluated by the 2nd order Grüneisen approximation using the Debye formalism for internal energy and intrinsic anharmonicity contributions. A relatively high Debye temperature θD = 689 ± 71 K was determined. The thermal behavior of cation-anion bond lengths in octahedral and tetrahedral environments is discussed. The lithium diffusion pathway in Li4Ti5O12 was discussed on the basis of bond-valence modeling.

  8. Neutron diffraction studies of magnetic ordering in Ni-doped LaCoO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rajeevan, N.E. [Department of Physics, Z.G. College, Calicut 673014, Kerala (India); Kumar, Vinod; Kumar, Rajesh [Department of Physics, National Institute of Technology, Hamirpur 177005, Himachal Pradesh (India); Kumar, Ravi [Beant College of Engineering and Technology, Gurudaspur 143521, Punjab (India); Kaushik, S.D. [UGC-DAE CSR Mumbai Centre, R-5 Shed, BARC, Mumbai 400085, Maharashtra (India)

    2015-11-01

    Research in rare earth cobaltite has recently been intensified due to its fascinating magnetic properties. LaCoO{sub 3}, an important cobaltite, exhibits two prominent susceptibility features at ~90 K and 500 K in low field measurement. The magnetic behavior below 100 K is predominantly antiferromagnetic (AFM), but absence of pure AFM ordering and emergence of ferromagnetic coupling on further decreasing temperature made situation more intricate. The present work of studying the effect of Ni substitution at Co site in polycrystalline LaCo{sub 1−x}Ni{sub x}O{sub 3} (0≤x≤0.3) is motivated by the interesting changes in magnetic and electronic properties. For lucid understanding, temperature dependent neutron diffraction (ND) study was carried out. ND patterns fitted with rhombohedral structure in perovskite form with R-3c space group, elucidated information on phase purity. Further temperature dependent cell parameter, Co–O bond-length and Co–O–Co bond angle were calculated for the series of Ni doped LaCoO{sub 3}. The results are explained in terms of decrease in the crystal field energy which led to the transition of cobalt from low Spin (LS) state to intermediate spin state (IS). - Highlights: • Temperature dependent neutron diffraction (ND) on Ni doped LaCoO{sub 3} are studied. • Microscopic parameters (cell, bond length, bond angle etc.) are determined by ND. • Increase in Co–O bond length and decrease in Co–O–Co bond angle on Ni substitution. • Ionic radii of Co{sup +3} in IS state (0.56 Å) is larger than in LS state (0.54 Å). • Lattice expansion induced increase in Co–O length stabilizes Co{sup +3} in magnetic state.

  9. In situ neutron diffraction studies of operating MGA thermal storage materials

    Directory of Open Access Journals (Sweden)

    Sugo Heber

    2017-01-01

    Full Text Available Miscibility Gap Alloys (MGA store energy as the latent heat of fusion of a discrete component within an engineered multicomponent microstructure. The thermal energy density is augmented by the associated sensible heat of the whole alloy. MGA microstructures are organised so that the low melting point component, acting as a Phase Change Material (PCM, is present as dispersed, non-intersecting particles within a continuous 3-dimensional solid matrix of a higher melting point component. The primary advantages of such an arrangement are the high thermal conductivity, 60–200 W/m K and high energy density (0.25–1.26 MJ/L. Long service life, low maintenance and the resulting simplified infrastructure offered by the ability of the MGA storage materials to exchange heat via conduction alone are further notable benefits. Unlike sensible heat storage materials, temperature measurement alone cannot indicate the state-of-charge of PCM storage since the temperature remains relatively constant throughout the melting or freezing transition. The work reported here addresses this issue through the use of in situ neutron diffraction to determine the relative volume fractions of solid (crystalline and liquid PCM within the MGA material as a function of varying temperature conditions. The aim is to provide calibration data for state-of-charge thermal models of PCM storage systems. Preliminary analysis of the neutron diffraction results and associated thermal measurements from a series of experiments carried out using the KOWARI diffractometer at the Australian Nuclear Science and Technology Organisation are presented in this work.

  10. Magnetic phases in the Kagomé staircase compound Co3V2O8 studied using powder neutron diffraction

    Science.gov (United States)

    Wilson, N. R.; Petrenko, O. A.; Chapon, L. C.

    2007-03-01

    The low temperature properties of the Kagomé-type system Co3V2O8 have been studied by powder neutron diffraction both in zero field and in applied magnetic fields of up to 8T . Below 6K , the zero-field ground state is ferromagnetic with the magnetic moments aligned along the a axis. The size of the moment on one of the two Co sites, the so-called cross-tie site, is considerably reduced compared to the fully polarized state. The application of a magnetic field in this phase is found to rapidly enhance the cross-tie site magnetic moment, which reaches the expected value of ˜3μB by the maximum applied field of 8T . Different reorientation behaviors are found for the Co cross-tie and spine sites, suggesting a more pronounced easy-axis anisotropy for moments on the spine sites. Rietveld refinements reveal that a simple model, where the spins on both cross-tie and spine sites rotate in the ac plane in a magnetic field, reproduces the experimental diffraction patterns well. In addition, it is found that at higher temperatures and moderate magnetic fields, the incommensurate antiferromagnetic order, corresponding to a transverse sinusoidal modulation above 8K , is suppressed to be replaced by ferromagnetic order.

  11. Neutron diffraction study of aqueous Laponite suspensions at the NIMROD diffractometer

    Science.gov (United States)

    Tudisca, V.; Bruni, F.; Scoppola, E.; Angelini, R.; Ruzicka, B.; Zulian, L.; Soper, A. K.; Ricci, M. A.

    2014-09-01

    The process of dynamical arrest, leading to formation of different arrested states such as glasses and gels, along with the closely related process of aging, is central for both basic research and technology. Here we report on a study of the time-dependent structural evolution of two aqueous Laponite clay suspensions at different weight concentrations. Neutron diffraction experiments have been performed with the near and intermediate range order diffractometer (NIMROD) that allows studies of the structure of liquids and disordered materials over a continuous length scale ranging from 1 to 300 Å, i.e., from the atomistic to the mesoscopic scales. NIMROD is presently a unique diffractometer, bridging the length scales traditionally investigated by small angle neutron scattering or small angle x-ray scattering with that accessible by traditional diffractometers for liquids. Interestingly, we have unveiled a signature of aging of both suspensions in the length scale region of NIMROD. This phenomenon, ascribed to sporadic contacts between Laponite platelets at long times, has been observed with the sample arrested as gel or as repulsive glass. Moreover, water molecules within the layers closest to Laponite platelets surface show orientational and translational order, which maps into the crystalline structure of Laponite.

  12. Neutron diffraction study of δ-alloy Pu{sup 242}–Ga aging

    Energy Technology Data Exchange (ETDEWEB)

    Somenkov, V.A. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Blanter, M.S., E-mail: mike.blanter@gmail.com [Moscow State University of Instrumental Engineering and Information Science, Moscow (Russian Federation); Glazkov, V.P. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Laushkin, A.V.; Orlov, V.K. [JSC VNIINM n.a. A.A. Bochvar, Moscow (Russian Federation)

    2014-09-15

    In this paper, we report on a continuing neutron diffraction study of the mean-square atom displacements occurring during the long-term self-irradiation of a Pu–Ga alloy. The measurements were performed at room temperature using the sample based on the isotope Pu{sup 242} with low neutron absorption cross-section to which the short-lived isotope Pu{sup 238} (1.4 wt.%) was added to accelerate self-irradiation. We obtain the maximum self-irradiation equivalent time of 35.5 years, 12 years longer than in our previous papers. In the entire range of self-irradiation time a single fcc phase is preserved. It was found that after the two stages of change in the mean-square displacements we observed earlier (rapid growth up to ∼5–6 equivalent years and a slow decline in the range of ∼6–25 years), comes a stage of stabilization (after ∼25 years). The stabilization can be explained by the emergence of a balance between the formation of point defects and their absorption by helium bubbles and dislocation loops which accumulated over time.

  13. Residual stress determination in a dissimilar weld overlay pipe by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Wanchuck, E-mail: chuckwoo@kaeri.re.kr [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Em, Vyacheslav [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Hubbard, Camden R. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Lee, Ho-Jin [Nuclear Materials Research Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Kwang Soo [Corporate R and D Institute, Doosan Heavy Industries and Construction, Changwon 641-792 (Korea, Republic of)

    2011-10-15

    Highlights: {yields} Determined residual stress distribution in a dissimilar weld overlay pipe. {yields} Consists of a ferritic (SA508), austenitic (F316L) steels, Alloy 182 consumable. {yields} Measured significant compression (-600 MPa) near the inner wall of overlay. {yields} Validate integrity of the inner wall for the pressurized nozzle nuclear structure. - Abstract: Residual stresses were determined through the thickness of a dissimilar weld overlay pipe using neutron diffraction. The specimen has a complex joining structure consisting of a ferritic steel (SA508), austenitic steel (F316L), Ni-based consumable (Alloy 182), and overlay of Ni-base superalloy (Alloy 52M). It simulates pressurized nozzle components, which have been a critical issue under the severe crack condition of nuclear power reactors. Two neutron diffractometers with different spatial resolutions have been utilized on the identical specimen for comparison. The macroscopic 'stress-free' lattice spacing (d{sub o}) was also obtained from both using a 2-mm width comb-like coupon. The results show significant changes in residual stresses from tension (300-400 MPa) to compression (-600 MPa) through the thickness of the dissimilar weld overlay pipe specimen.

  14. Temperature effects on the structure of liquid D-methanol through neutron diffraction

    Indian Academy of Sciences (India)

    A Sahoo; S Sarkar; P S R Krishna; R N Joarder

    2004-08-01

    The study of changes in the structure (H-bonded) of liquid alcohols at elevated temperatures is rare probably due to low flash points of these liquids. An indigenously devised special quartz cell is now used to carry out the structural studies of these liquids at elevated temperatures through neutron diffraction. Here, the liquid consists of deuterated methanol and neutron data was collected on the high- diffractometer at Dhruva, BARC. The corrected data at elevated temperatures (BP (boiling point) and double the BP) show that there is a large change in the H-bonded structure of this liquid. The pre-peak or hump, known to be signature of H-bonded clusters appears to be present at all the three temperatures studied. In the low- (scattering vector) data Ornstein-Zernike (OZ) behaviour is also observed. It is, however, seen that the intramolecular structure does not change very much at higher temperatures. A detailed model analysis is in progress and would be reported later.

  15. Polymorphism in Photoluminescent KNdW2O8: Synthesis, Neutron Diffraction, and Raman Study

    Energy Technology Data Exchange (ETDEWEB)

    S. M. Bhat, Swetha [Materials Science Division, Poornaprajna Institute of Scientific Research, Bidalur Near Devanahalli,; Swain, Diptikanta [CPMU, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru, Karnataka, India; Feygenson, Mikhail [ORNL; Neuefeind, Joerg C [ORNL; Sundaram, Nalini [Materials Science Division, Poornaprajna Institute of Scientific Research, Bidalur Near Devanahalli,

    2014-01-01

    Polymorphs of KNdW2O8 ( -KNdW2O8 and -KNdW2O8) phosphors were synthesized by an efficient solution combustion technique for the first time. The crystal structure of the polymorphs analyzed from Rietveld refinement of neutron diffraction data confirms that -KNdW2O8 crystallizes in the tetragonal system (space group I4 ), and -KNdW2O8 crystallizes in the monoclinic system (space group C2/m). The local structure of both polymorphs was elucidated using combined neutron pair distribution function (PDF) and Raman scattering techniques. Photoluminescence measurements of the polymorphs showed broadened emission line width and increased intensity for -KNdW2O8 in the visible region compared to -KNdW2O8. This phenomenon is attributed to the increased distortion in the coordination environment of the luminescing Nd3+ ion. Combined PDF, Rietveld, and Raman measurements reveal distortions of the WO6 octahedra and NdO8 polyhedra in -KNdW2O8. This crystal structure photoluminescence study suggests that this class of tungstates can be exploited for visible light emitting devices by tuning the crystal symmetry.

  16. 14 MeV neutrons physics and applications

    CERN Document Server

    Valkovic, Vladivoj

    2015-01-01

    Despite the often difficult and time-consuming effort of performing experiments with fast (14 MeV) neutrons, these neutrons can offer special insight into nucleus and other materials because of the absence of charge. 14 MeV Neutrons: Physics and Applications explores fast neutrons in basic science and applications to problems in medicine, the environment, and security.Drawing on his more than 50 years of experience working with 14 MeV neutrons, the author focuses on:Sources of 14 MeV neutrons, including laboratory size accelerators, small and sealed tube generators, well logging sealed tube ac

  17. Thermodynamic and neutron diffraction studies on multiferroic NdMn{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S.; Balédent, V.; Auban-Senzier, P.; Pasquier, C.; Doubrovsky, C. [Laboratoire de Physique des Solides, Université Paris-Sud, CNRS-UMR 8502, 91405 Orsay (France); Greenblatt, M. [Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Foury-Leylekian, P., E-mail: pascale.foury@u-psud.fr [Laboratoire de Physique des Solides, Université Paris-Sud, CNRS-UMR 8502, 91405 Orsay (France)

    2015-03-01

    Magnetically frustrated RMn{sub 2}O{sub 5} oxides have attracted considerable attention in recent years, because most of the members of this family show spin ordering induced dielectric polarization along with strong magneto-electric coupling. Although the true origin of the ferroelectricity is still a matter of debate, it has been observed that the magneto-electric phase diagram can be substantially tuned with the variation of rare earth elements. In this work, we have chosen NdMn{sub 2}O{sub 5} as the compound of our interest since it lies exactly in between the ferroelectric and non-ferroelectric members of this family and also, because there are few investigations performed on RMn{sub 2}O{sub 5} systems with large rare earth atoms . With the combination of heat capacity, magnetic susceptibility, dielectric permittivity, powder X-ray diffraction, and powder neutron diffraction measurements, it has been found that NdMn{sub 2}O{sub 5} undergoes an incommensurate magnetic ordering around 30 K followed by a possible ferroelectric-like transition at ∼26 K. Another lock-in kind of magnetic transition appears when the temperature is decreased to ∼15 K. With further lowering of temperature, an antiferromagnetic ordering, which is presumably associated with the Nd{sup 3+}, is achieved near 4 K. This study thus sheds light on a new compound of the RMn{sub 2}O{sub 5} series presenting different multiferroic properties.

  18. Thermodynamic and neutron diffraction studies on multiferroic NdMn2O5

    Science.gov (United States)

    Chattopadhyay, S.; Balédent, V.; Auban-Senzier, P.; Pasquier, C.; Doubrovsky, C.; Greenblatt, M.; Foury-Leylekian, P.

    2015-03-01

    Magnetically frustrated RMn2O5 oxides have attracted considerable attention in recent years, because most of the members of this family show spin ordering induced dielectric polarization along with strong magneto-electric coupling. Although the true origin of the ferroelectricity is still a matter of debate, it has been observed that the magneto-electric phase diagram can be substantially tuned with the variation of rare earth elements. In this work, we have chosen NdMn2O5 as the compound of our interest since it lies exactly in between the ferroelectric and non-ferroelectric members of this family and also, because there are few investigations performed on RMn2O5 systems with large rare earth atoms . With the combination of heat capacity, magnetic susceptibility, dielectric permittivity, powder X-ray diffraction, and powder neutron diffraction measurements, it has been found that NdMn2O5 undergoes an incommensurate magnetic ordering around 30 K followed by a possible ferroelectric-like transition at ∼26 K. Another lock-in kind of magnetic transition appears when the temperature is decreased to ∼15 K. With further lowering of temperature, an antiferromagnetic ordering, which is presumably associated with the Nd3+, is achieved near 4 K. This study thus sheds light on a new compound of the RMn2O5 series presenting different multiferroic properties.

  19. Neutron diffraction studies on magnetic properties of Ca5Ni4V6O24

    Science.gov (United States)

    Sharma, Shivani; Singh, Kiran; Lalla, N. P.; Suard, E.; Simon, Ch.

    2017-01-01

    The temperature dependent neutron powder diffraction (NPD) and magnetization measurements of vanadium based garnet Ca5Ni4V6O24 (CNVO) have been performed to explore its crystal and magnetic structures. The magnetization results illustrate two magnetic anomalies at 7 and 4 K. The Rietveld analysis of room temperature x-ray diffraction and NPD data confirms its Ia-3d crystal structure. The temperature dependent NPD shows the emergence of magnetic reflections below 7 K whose intensity keeps on increasing with decreasing temperature down to 1.5 K. The crystal structure remains cubic down to 1.5 K. Rietveld analysis reveals that below 7 K, the Ni moments in CNVO undergo a commensurate collinear A-type antiferromagnetic ordering with propagation vector k=(0,0,0) and the per site ordered moment of Ni2+ is 1.69±0.05 μB. Absence of any additional magnetic or nuclear reflections below 4 K confirms that the nuclear and magnetic structures remain invariant across the 4 K magnetic anomaly.

  20. Structure of naturally hydrated ferrihydrite revealed through neutron diffraction and first-principles modeling

    Science.gov (United States)

    Chappell, Helen F.; Thom, William; Bowron, Daniel T.; Faria, Nuno; Hasnip, Philip J.; Powell, Jonathan J.

    2017-08-01

    Ferrihydrite, with a ``two-line'' x-ray diffraction pattern (2L-Fh), is the most amorphous of the iron oxides and is ubiquitous in both terrestrial and aquatic environments. It also plays a central role in the regulation and metabolism of iron in bacteria, algae, higher plants, and animals, including humans. In this study, we present a single-phase model for ferrihydrite that unifies existing analytical data while adhering to fundamental chemical principles. The primary particle is small (20-50 Å) and has a dynamic and variably hydrated surface, which negates long-range order; collectively, these features have hampered complete characterization and frustrated our understanding of the mineral's reactivity and chemical/biochemical function. Near and intermediate range neutron diffraction (NIMROD) and first-principles density functional theory (DFT) were employed in this study to generate and interpret high-resolution data of naturally hydrated, synthetic 2L-Fh at standard temperature. The structural optimization overcomes transgressions of coordination chemistry inherent within previously proposed structures, to produce a robust and unambiguous single-phase model.

  1. Potassium Disorder in the Defect Pyrochlore KSbTeO6: A Neutron Diffraction Study

    Directory of Open Access Journals (Sweden)

    José Antonio Alonso

    2017-01-01

    Full Text Available KSbTeO6 defect pyrochlore has been prepared from K2C2O4, Sb2O3, and 15% excess TeO2 by solid-state reaction at 850 °C. Direct methods implemented in the software EXPO2013 allowed establishing the basic structural framework. This was followed by a combined Rietveld refinement from X-ray powder diffraction (XRD and neutron powder diffraction (NPD data, which unveiled additional structural features. KSbTeO6 is cubic, a = 10.1226(7 Å, space group F d 3 ¯ m , Z = 8 and it is made of a mainly covalent framework of corner-sharing (Sb,TeO6 octahedra, with weakly bonded K+ ions located within large cages. The large K-O distances, 3.05(3–3.07(3 Å, and quite large anisotropic atomic displacement parameters account for the easiness of K+ exchange for other cations of technological importance.

  2. Cold Drawn Steel Wires-Processing, Residual Stresses and Ductility Part II: Synchrotron and Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Phelippeau,A.; Pommier, S.; Zakharchenko, I.; Levy-Tubiana, R.; Tsakalakos, T.; Clavel, M.; Croft, M.; Zhong, Z.; Prioul, C.

    2006-01-01

    Cold drawing of steel wires leads to an increase of their mechanical strength and to a drop in their ductility. The increase of their mechanical strength has long been related to the reduction of the various material scales by an intense plastic deformation. Besides, it was discussed in the companion paper that large plastic deformation leads to the loss of the material hardening capabilities and that, in such a case, residual stresses preserve the elongation to failure of wires. Experimental measurements of residual stresses inside the wire have therefore been undertaken. In this paper, lattice parameters as measured using synchrotron diffraction are compared with those calculated using the residual stress fields as determined by the finite-element method. There is a major disagreement between experimental and numerical results that is too large to be attributed to the errors of the finite-element analyses. Therefore, neutron diffraction experiments have also been performed. These measurements show that there is a significant variation of the lattice parameter with the drawing level, which is not inherited from residual stresses, and that variation is very sensitive to the cooling rate after processing. It is therefore proposed that cold drawing would induce a phase transformation of the steel, possibly a martensitic transformation.

  3. Optimizations in angular dispersive neutron powder diffraction using divergent beam geometries

    Science.gov (United States)

    Buchsteiner, Alexandra; Stüßer, Norbert

    2009-01-01

    Angular dispersive neutron powder diffractometers are usually built using beam divergencies defined by Soller type collimators. To account for the needs of resolution for crystal structure refinement a good in-pile collimation α1, a high take-off angle above 90∘ at the monochromator and a good collimation α3 in front of the detector bank are chosen whereas the value of α2 for the collimation between monochromator and sample is less crucial. During the last years new strategies were developed at our institute using wide divergent beam geometries defined by fan collimators or slit-type diaphragms which correlate ray direction and wavelength within the beam. Here we present the performance of a newly developed fan collimator, which enables one to adjust the opening of the collimator channels on both sides independently. This fan collimator is positioned in front of the monochromator at the instrument E6 at the Helmholtz Centre Berlin (formerly Hahn-Meitner-Institut Berlin). It will be shown that control of the beam divergency allows optimization of the resolution in a large angular diffraction range. Hence the resolution and intensity can be adapted to the needs of powder diffraction. Monte Carlo simulations using McStas are used to check and prove the optimal setting of the instrument. We obtain a very good agreement between experimental and simulated data and demonstrate the superior outcome of the new instrument configuration with respect to Soller type instruments.

  4. Optimizations in angular dispersive neutron powder diffraction using divergent beam geometries

    Energy Technology Data Exchange (ETDEWEB)

    Buchsteiner, Alexandra [Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, D-14109 Berlin (Germany)], E-mail: buchsteiner@helmholtz-berlin.de; Stuesser, Norbert [Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, D-14109 Berlin (Germany)

    2009-01-11

    Angular dispersive neutron powder diffractometers are usually built using beam divergencies defined by Soller type collimators. To account for the needs of resolution for crystal structure refinement a good in-pile collimation {alpha}{sub 1}, a high take-off angle above 90 deg. at the monochromator and a good collimation {alpha}{sub 3} in front of the detector bank are chosen whereas the value of {alpha}{sub 2} for the collimation between monochromator and sample is less crucial. During the last years new strategies were developed at our institute using wide divergent beam geometries defined by fan collimators or slit-type diaphragms which correlate ray direction and wavelength within the beam. Here we present the performance of a newly developed fan collimator, which enables one to adjust the opening of the collimator channels on both sides independently. This fan collimator is positioned in front of the monochromator at the instrument E6 at the Helmholtz Centre Berlin (formerly Hahn-Meitner-Institut Berlin). It will be shown that control of the beam divergency allows optimization of the resolution in a large angular diffraction range. Hence the resolution and intensity can be adapted to the needs of powder diffraction. Monte Carlo simulations using McStas are used to check and prove the optimal setting of the instrument. We obtain a very good agreement between experimental and simulated data and demonstrate the superior outcome of the new instrument configuration with respect to Soller type instruments.

  5. A large volume cell for in situ neutron diffraction studies of hydrothermal crystallizations

    Science.gov (United States)

    Xia, Fang; Qian, Gujie; Brugger, Joël; Studer, Andrew; Olsen, Scott; Pring, Allan

    2010-10-01

    A hydrothermal cell with 320 ml internal volume has been designed and constructed for in situ neutron diffraction studies of hydrothermal crystallizations. The cell design adopts a dumbbell configuration assembled with standard commercial stainless steel components and a zero-scattering Ti-Zr alloy sample compartment. The fluid movement and heat transfer are simply driven by natural convection due to the natural temperature gradient along the fluid path, so that the temperature at the sample compartment can be stably sustained by heating the fluid in the bottom fluid reservoir. The cell can operate at temperatures up to 300 °C and pressures up to 90 bars and is suitable for studying reactions requiring a large volume of hydrothermal fluid to damp out the negative effect from the change of fluid composition during the course of the reactions. The capability of the cell was demonstrated by a hydrothermal phase transformation investigation from leucite (KAlSi2O6) to analcime (NaAlSi2O6ṡH2O) at 210 °C on the high intensity powder diffractometer Wombat in ANSTO. The kinetics of the transformation has been resolved by collecting diffraction patterns every 10 min followed by Rietveld quantitative phase analysis. The classical Avrami/Arrhenius analysis gives an activation energy of 82.3±1.1 kJ mol-1. Estimations of the reaction rate under natural environments by extrapolations agree well with petrological observations.

  6. Uranium and thorium hydride complexes as multielectron reductants: a combined neutron diffraction and quantum chemical study.

    Science.gov (United States)

    Grant, Daniel J; Stewart, Timothy J; Bau, Robert; Miller, Kevin A; Mason, Sax A; Gutmann, Matthias; McIntyre, Garry J; Gagliardi, Laura; Evans, William J

    2012-03-19

    The unusual uranium reaction system in which uranium(4+) and uranium(3+) hydrides interconvert by formal bimetallic reductive elimination and oxidative addition reactions, [(C(5)Me(5))(2)UH(2)](2) (1) ⇌ [(C(5)Me(5))(2)UH](2) (2) + H(2), was studied by employing multiconfigurational quantum chemical and density functional theory methods. 1 can act as a formal four-electron reductant, releasing H(2) gas as the byproduct of four H(2)/H(-) redox couples. The calculated structures for both reactants and products are in good agreement with the X-ray diffraction data on 2 and 1 and the neutron diffraction data on 1 obtained under H(2) pressure as part of this study. The interconversion of the uranium(4+) and uranium(3+) hydride species was calculated to be near thermoneutral (~-2 kcal/mol). Comparison with the unknown thorium analogue, [(C(5)Me(5))(2)ThH](2), shows that the thorium(4+) to thorium(3+) hydride interconversion reaction is endothermic by 26 kcal/mol.

  7. Magnetoelastic effect in MF{sub 2} (M = Mn, Fe, Ni) investigated by neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chatterji, Tapan [JCNS, Forschungszentrum Juelich Outstation at Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Iles, Gail N; Ouladdiaf, Bachir; Hansen, Thomas C [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2010-08-11

    We have investigated the magnetoelastic effects in MF{sub 2} (M = Mn, Fe, Ni) associated with the antiferromagnetic phase transition temperature T{sub N} by neutron powder diffraction. The temperature variation of the lattice parameters and the unit cell volume has been determined accurately with small temperature steps. From the temperature variation of the lattice parameters a, c and V the lattice strains {Delta}a, {Delta}c and {Delta}V associated with the antiferromagnetic phase transition have been extracted. Rietveld refinement of the crystal and magnetic structures from the diffraction data at low temperature gave a magnetic moment of 5.12 {+-} 0.09 {mu}{sub B}, 4.05 {+-} 0.05 {mu}{sub B} and 1.99 {+-} 0.05 {mu}{sub B} per Mn, Fe and Ni ions, respectively. The lattice strains {Delta}a, {Delta}c and {Delta}V couple linearly with the intensity of the 100 magnetic reflection, which is proportional to square of the order parameter of the antiferromagnetic phase transition. The volume strains in MF{sub 2} (M = Mn, Fe, Co, Ni) due to the magnetostriction vary smoothly along the transition metal series and seem to be correlated with the strength of the exchange interaction and the moments of the magnetic ions.

  8. Neutron applications in earth, energy and environmental sciences

    CERN Document Server

    Liang, Liyuan; Schober, Helmut

    2009-01-01

    This text is a comprehensive overview of neutron scattering techniques that enhance the study of materials at the micro and nanoscale. The well structured volume provides introductions to various neutron applications from leading experts in the field.

  9. A Neutron Diffraction Study of the Nuclear and Magnetic Structure of MnNb2O6

    DEFF Research Database (Denmark)

    Nielsen, Oliver Vindex; Lebech, Bente; Krebs Larsen, F.;

    1976-01-01

    A neutron diffraction study was made of the nuclear and the magnetic structure of MnNb2O6 single crystals. The thirteen nuclear parameters (space group Pbcn) were determined from 304 reflections at room temperature. The antiferromagnetic structure (Neel temperature=4.4K), determined at 1.2K, is a...

  10. Low temperature neutron diffraction data for CeCo{sub 0.86}Ge{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gil, A. [Department of Mathematics and Natural Sciences, Pedagogical University, Armii Krajowej 13/15, 42-800 Czestochowa (Poland); Penc, B. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Crakow (Poland); Hernandez-Velasco, J. [Berlin Neutron Scattering Center, Hahn-Meitner Institute, Glienicker Str. 100, D-14109 Berlin Wannsee (Germany); Wawrzynska, E. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow (Poland); Szytula, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow (Poland)]. E-mail: szytula@if.uj.ed.pl

    2005-01-25

    Neutron diffraction measurements have been performed on CeCo{sub 0.86}Ge{sub 2} at low temperatures. The obtained data confirm that this compound crystallizes in the orthorhombic CeNiSi{sub 2}-type structure (space group Cmcm). Magnetic ordering is not detected at 1.5 K.

  11. Single-crystal neutron diffraction studies on Ni-based metal-pnictide superconductor BaNi2As2

    Energy Technology Data Exchange (ETDEWEB)

    Kothapalli, Karunakar [Los Alamos National Laboratory; Ronning, F [Los Alamos National Laboratory; Bauer, E D [Los Alamos National Laboratory; Schultz, A J [Los Alamos National Laboratory; Nakotte, Heinz [Los Alamos National Laboratory

    2009-01-01

    We report the results of single-crystal neutron diffraction studies of the superconductor BaNi{sub 2}As{sub 2}. The experiments were performed on a tiny crystal of mass 0.8 mg at several temperatures between 20 and 200 K using the Single Crystal Diffractometer, SCD, at the Los Alamos Neutron Science Center. Above 130 K, BaNi{sub 2}As{sub 2} crystallizes in the tetragonal ThCr{sub 2}Si{sub 2} structure. Our neutron diffraction data corroborate a first-order structural transition around 130 K with a relatively large hysteresis of about 10K, in agreement with observations from bulk studies. The anisotropic thermal displacement coefficients are enhanced along c-axis approaching the transition, and a splitting is observed for in-plane type reflections below the transition, which is evidence for a change in crystal structure.

  12. Non-destructive Quantitative Phase Analysis and Microstructural Characterization of Zirconium Coated U-10Mo Fuel Foils via Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, Dustin Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hollis, Kendall Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brown, Donald William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dombrowski, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-18

    This report uses neutron diffraction to investigate the crystal phase composition of uranium-molybdenum alloy foils (U-10Mo) for the CONVERT MP-1 Reactor Conversion Project, and determines the effect on alpha-uranium contamination following the deposition of a Zr metal diffusion layer by various methods: plasma spray deposition of Zr powders at LANL and hot co-rolling with Zr foils at BWXT. In summary, there is minimal decomposition of the gamma phase U-10Mo foil to alpha phase contamination following both plasma spraying and hot co-rolling. The average unit cell volume, i.e. lattice spacing, of the Zr layer can be mathematically extracted from the diffraction data; co-rolled Zr matches well with literature values of bulk Zr, while plasma sprayed Zr shows a slight increase in the lattice spacing, indicative of interstitial oxygen in the lattice. Neutron diffraction is a beneficial alternative to conventional methods of phase composition, i.e. x ray diffraction (XRD) and destructive metallography. XRD has minimal penetration depth in high atomic number materials, particularly uranium, and can only probe the first few microns of the fuel plate; neutrons pass completely through the foil, allowing for bulk analysis of the foil composition and no issues with addition of cladding layers, as in the final, aluminum-clad reactor fuel plates. Destructive metallography requires skilled technicians, cutting of the foil into small sections, hazardous etching conditions, long polishing and microscopy times, etc.; the neutron diffraction system has an automated sample loader and can fit larger foils, so there is minimal analysis preparation; the total spectrum acquisition time is ~ 1 hour per sample. The neutron diffraction results are limited by spectra refinement/calculation times and the availability of the neutron beam source. In the case of LANSCE at Los Alamos, the beam operates ~50% of the year. Following the lessons learned from these preliminary results, optimizations to

  13. Non-destructive Quantitative Phase Analysis and Microstructural Characterization of Zirconium Coated U-10Mo Fuel Foils via Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, Dustin Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hollis, Kendall Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brown, Donald William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dombrowski, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-18

    This report uses neutron diffraction to investigate the crystal phase composition of uranium-molybdenum alloy foils (U-10Mo) for the CONVERT MP-1 Reactor Conversion Project and determines the effect on alpha uranium contamination following the deposition of a Zr metal diffusion layer by various methods: plasma spray deposition of Zr powders at LANL and hot co-rolling with Zr foils at BWXT. In summary, there is minimal decomposition of the gamma phase U-10Mo foil to alpha phase contamination following both plasma spraying and hot co-rolling. The average unit cell volume, i.e. lattice spacing, of the Zr layer can be mathematically extracted from the diffraction data; co-rolled Zr matches well with literature values of bulk Zr, while plasma sprayed Zr shows a slight increase in the lattice spacing, indicative of interstitial oxygen in the lattice. Neutron diffraction is a beneficial alternative to conventional methods of phase composition, i.e. x ray diffraction (XRD) and destructive metallography. XRD has minimal penetration depth in high atomic number materials, particularly uranium, and can only probe the first few microns of the fuel plate; neutrons pass completely through the foil, allowing for bulk analysis of the foil composition and no issues with addition of cladding layers, as in the final, aluminum clad reactor fuel plates. Destructive metallography requires skilled technicians, cutting of the foil into small sections, hazardous etching conditions, long polishing and microscopy times, etc.; the neutron diffraction system has an automated sample loader and can fit larger foils, so there is minimal analysis preparation; the total spectrum acquisition time is ~ 1 hour per sample. The neutron diffraction results are limited by spectra refinement/calculation times and the availability of the neutron beam source. In the case of LANSCE at Los Alamos, the beam operates ~50% of the year. Following the lessons learned from these preliminary results, optimizations to

  14. Application Guide to Neutron Multiplicity Counting

    Energy Technology Data Exchange (ETDEWEB)

    D. G. Langner; J. E. Stewart; M. M. Pickrell; M. S. Krick; N. Ensslin; W. C. Harker

    1998-11-01

    This document is intended to serve as a comprehensive applications guide to passive neutron multiplicity counting, a new nondestructive assay (NDA) technique developed over the past ten years. The document describes the principles of multiplicity counter design, electronics, and mathematics. Existing counters in Department of Energy (DOE) facilities are surveyed, and their operating requirements and procedures and defined. Current applications to plutonium material types found in DOE facilities are described, and estimates of the expected assay precision and bias are given. Lastly, guidelines for multiplicity counter selection and procurement are summarized. The document also includes a detailed collection of references on passive neutron coincidence and multiplicity publications over the last ten to fifteen years.

  15. Neutron capture therapy. Principles and applications

    Energy Technology Data Exchange (ETDEWEB)

    Sauerwein, Wolfgang A.G. [University Hospital Duisburg-Essen Univ., Essen (Germany). Dept. of Radiation Oncology; Moss, Raymond [European Commission, Petten (Netherlands). Inst. for Energy; Wittig, Andrea [Marburg Univ. (Germany). Dept. of Radiotherapy and Radiation Oncology; Nakagawa, Yoshinobu (eds.) [Kagawa National Children' s Hospital, Zentsuji, Kagawa (Japan). Dept. of Neurosurgery

    2012-07-01

    State of the art report on neutron capture therapy. Summarizes the progress made in recent decades. Multidisciplinary approach. Written by the most experienced specialists Neutron capture therapy (NCT) is based on the ability of the non-radioactive isotope boron-10 to capture thermal neutrons with very high probability and immediately to release heavy particles with a path length of one cell diameter. This in principle allows for tumor cell-selective high-LET particle radiotherapy. NCT is exciting scientifically but challenging clinically, and a key factor in success is close collaboration among very different disciplines. This book provides a comprehensive summary of the progress made in NCT in recent years. Individual sections cover all important aspects, including neutron sources, boron chemistry, drugs for NCT, dosimetry, and radiation biology. The use of NCT in a variety of malignancies and also some non-malignant diseases is extensively discussed. NCT is clearly shown to be a promising modality at the threshold of wider clinical application. All of the chapters are written by experienced specialists in language that will be readily understood by all participating disciplines.

  16. Neutron diffraction and magnetic investigations of the TbCo sub 4 M compounds (M = Al and Ga)

    CERN Document Server

    Zlotea, C

    2002-01-01

    The structural and magnetic features of the TbCo sub 4 M compounds (M = Al and Ga) have been studied by means of neutron powder diffraction and magnetic measurements. X-ray diffraction experiments show that the samples are single phased, crystallizing in the CaCu sub 5 -type structure. Neutron powder diffraction measurements demonstrate a preferential substitution of Al and Ga at the 3g crystallographic site of the CaCu sub 5 -type structure. Together with neutron powder diffraction investigations, magnetization measurements and x-ray powder diffraction studies performed on field-oriented samples are combined in order to clarify the effects of the Al and Ga substitutions on the magnetic features of these compounds. The modifications of the magnetic properties upon substitution are significant: a drastic decrease of the mean Co magnetic moment and of the Curie temperature is observed. Unlike what was found earlier for TbCo sub 5 , no sign of a spin reorientation transition has been observed in the present TbCo...

  17. EuTiO3 magnetic structure studied by neutron powder diffraction and resonant x-ray scattering

    Science.gov (United States)

    Scagnoli, Valerio; Allieta, Mattia; Walker, Helen; Scavini, Marco; Katsufuji, Takuro; Sagarna, Leyre; Zaharko, Oksana; Mazzoli, Claudio

    2012-09-01

    We combine neutron powder diffraction and x-ray single-crystal magnetic diffraction at the Eu L2 edge to scrutinize the magnetic motif of the Eu ions in magnetoelectric EuTiO3. Our measurements are consistent with an antiferromagnetic G-type pattern with the Eu magnetic moments ordering along the a,b-plane diagonal. Recent reports of a novel transition at 2.75 K with a flop of magnetic moments upon poling the sample in an electric field cannot be confirmed for a nonpoled sample. Our neutron diffraction data do not show any significant change of the structure below the Néel temperature. Magnetoelastic coupling, if present, is therefore expected to be negligible.

  18. Monomer diffusion in sustainable photopolymers for diffractive optics applications

    OpenAIRE

    Gallego Rico, Sergi; Márquez Ruiz, Andrés; Ortuño Sánchez, Manuel; Marini, Stephan; Pascual Villalobos, Inmaculada; Beléndez Vázquez, Augusto

    2011-01-01

    Photopolymers have many applications in optics. However, one of the main drawbacks of these materials is the high toxicity of their components. One of the most widely studied photopolymers is polyvinyl-alcohol/acrylamide, and the carcinogenic potential of acrylamide is well known. In this paper we propose a new sustainable photopolymer as a substitute for acrylamide based photopolymers in the manufacture of diffractive optical elements. Diffraction efficiencies of around 40% were achieved for...

  19. Diffraction Gratings for High-Intensity Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  20. Other applications of neutron beams in material sciences; Autres utilisations des faisceaux de neutrons en science des materiaux

    Energy Technology Data Exchange (ETDEWEB)

    Novion, C.H. de

    1997-12-31

    The various applications of neutron beams are reviewed. The different mechanisms involved in neutron interaction with matter are explained. We notice that generally neutron radiation effects are unfavorable but can be turned into efficient tools to add new structures or properties to materials, silicon doping is an example. The basis principles of neutron activation analysis and neutron radiography are described. (A.C.)

  1. Carbonado revisited: Insights from neutron diffraction, high resolution orientation mapping and numerical simulations

    Science.gov (United States)

    Piazolo, Sandra; Kaminsky, Felix V.; Trimby, Patrick; Evans, Lynn; Luzin, V.

    2016-11-01

    One of the most controversial diamond types is carbonado, as its origin and geological history are still under debate. Here, we investigate selected carbonado samples using neutron diffraction and high resolution orientation mapping in combination with numerical simulations. Neutron diffraction analyses show that fine grained carbonado samples exhibit a distinct lack of crystallographic preferred orientation. Quantitative crystallographic orientation analyses performed on transmission electron microscope (TEM) sections reveal that the 2-10 μm grains exhibit locally significant internal deformation. Such features are consistent with crystal plastic deformation of a grain aggregate that initially formed by rapid nucleation, characterized by a high number of nucleation sites and no crystallographic preferred orientation. Crystal plastic deformation resulted in high stress heterogeneities close to grain boundaries, even at low bulk strains, inducing a high degree of lattice distortion without significant grain size reduction and the development of a crystallographic preferred orientation. Observed differences in the character of the grain boundary network and internal deformation structures can be explained by significant post-deformation annealing occurring to variable degrees in the carbonado samples. Differences in intensity of crystal bending and subgrain boundary sharpness can be explained by dislocation annihilation and rearrangement, respectively. During annealing grain energy is reduced resulting in distinct changes to the grain boundary geometry. Grain scale numerical modelling shows that anisotropic grain growth, where grain boundary energy is determined by the orientation of a boundary segment relative to the crystallographic orientation of adjacent grains results in straight boundary segments with abrupt changes in orientation even if the boundary is occurring between two triple junctions forming a "zigzag" pattern. In addition, in diamond anisotropic

  2. The temperature dependent structure of liquid 1-propanol as studied by neutron diffraction and EPSR simulations

    Science.gov (United States)

    Sillrén, Per; Swenson, Jan; Mattsson, Johan; Bowron, Daniel; Matic, Aleksandar

    2013-06-01

    The structure of liquid 1-propanol is investigated as a function of temperature using neutron diffraction together with Empirical Potential Structure Refinement modelling. The combined diffraction and computer modelling analysis demonstrates that propanol molecules form hydrogen bonded clusters with a relatively wide size distribution, which broadens at lower temperatures. We find that the cluster size distribution is well described by a recently proposed statistical model for branched H-bonded networks [P. Sillrén, J. Bielecki, J. Mattsson, L. Börjesson, and A. Matic, J. Chem. Phys. 136, 094514 (2012)], 10.1063/1.3690137. The average cluster size increases from ˜3 to 7 molecules, whilst the standard deviation of the size distribution increases from 3.3 to 8.5 as the temperature is decreased from 293 to 155 K. The clusters are slightly branched, with a higher degree of branching towards lower temperatures. An analysis of the cluster gyration tensor (Rmn) reveals an average elongated ellipsoidal shape with axes having proportions 1:1.4:1.9. We find that the average radius of gyration has a cluster size dependence consistent with that of fractal clusters, Rg ∝ n1/D, with a fractal dimension D ≈ 2.20, which is close to D = 2.00 expected for an ideal random walk or D = 2.11 expected for reaction limited aggregation. The characteristic angles between the H-bonded OH-groups that constitute the clusters show only a weak temperature dependence with O-H⋯O angles becoming more narrowly distributed around 180° at lower temperatures.

  3. Six-axis multi-anvil press for high-pressure, high-temperature neutron diffraction experiments.

    Science.gov (United States)

    Sano-Furukawa, A; Hattori, T; Arima, H; Yamada, A; Tabata, S; Kondo, M; Nakamura, A; Kagi, H; Yagi, T

    2014-11-01

    We developed a six-axis multi-anvil press, ATSUHIME, for high-pressure and high-temperature in situ time-of-flight neutron powder diffraction experiments. The press has six orthogonally oriented hydraulic rams that operate individually to compress a cubic sample assembly. Experiments indicate that the press can generate pressures up to 9.3 GPa and temperatures up to 2000 K using a 6-6-type cell assembly, with available sample volume of about 50 mm(3). Using a 6-8-type cell assembly, the available conditions expand to 16 GPa and 1273 K. Because the six-axis press has no guide blocks, there is sufficient space around the sample to use the aperture for diffraction and place an incident slit, radial collimators, and a neutron imaging camera close to the sample. Combination of the six-axis press and the collimation devices realized high-quality diffraction pattern with no contamination from the heater or the sample container surrounding the sample. This press constitutes a new tool for using neutron diffraction to study the structures of crystals and liquids under high pressures and temperatures.

  4. Six-axis multi-anvil press for high-pressure, high-temperature neutron diffraction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Sano-Furukawa, A., E-mail: sano.asami@jaea.go.jp; Hattori, T. [Quantum Beam Science Center, Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan); J-PARC Center, Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan); Arima, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Yamada, A. [The University of Shiga Prefecture, Shiga 522-8533 (Japan); Tabata, S.; Kondo, M.; Nakamura, A. [Sumitomo Heavy Industries Co., Ltd., Ehime 792-0001 (Japan); Kagi, H.; Yagi, T. [Geochemical Research Center, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan)

    2014-11-15

    We developed a six-axis multi-anvil press, ATSUHIME, for high-pressure and high-temperature in situ time-of-flight neutron powder diffraction experiments. The press has six orthogonally oriented hydraulic rams that operate individually to compress a cubic sample assembly. Experiments indicate that the press can generate pressures up to 9.3 GPa and temperatures up to 2000 K using a 6-6-type cell assembly, with available sample volume of about 50 mm{sup 3}. Using a 6-8-type cell assembly, the available conditions expand to 16 GPa and 1273 K. Because the six-axis press has no guide blocks, there is sufficient space around the sample to use the aperture for diffraction and place an incident slit, radial collimators, and a neutron imaging camera close to the sample. Combination of the six-axis press and the collimation devices realized high-quality diffraction pattern with no contamination from the heater or the sample container surrounding the sample. This press constitutes a new tool for using neutron diffraction to study the structures of crystals and liquids under high pressures and temperatures.

  5. Neutron diffraction studies on La2-DyCa2Ba2Cu4+2O superconductors

    Indian Academy of Sciences (India)

    S Rayaprol; Rohini Parmar; D G Kuberkar; Keka R Chakraborty; P S R Krishna; M Ramanadham

    2004-08-01

    Structural studies on Dy-substituted La-2125 type superconductors have been carried out by neutron diffraction experiments at room temperature using a monochromatic neutron beam of wavelength () = 1.249 Å. A series of samples with La2-DyCa2Ba2Cu4+2O stoichiometric composition, for = 0.1-0.5, have been studied for their structural properties. A tetragonal Y-123 unit cell was taken as the starting model for the Rietveld analysis. All the samples fit into the starting model, with no structural transition taking place with increasing dopant concentration. The results of Rietveld analysis and structural properties will be discussed in detail.

  6. Aerial Neutron Detection: Neutron Signatures for Nonproliferation and Emergency Response Applications

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Richard J.; Stampahar, Thomas G.; Smith, Ethan X.; Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Rourke, Timothy J.; LeDonne, Jeffrey P.; Avaro, Emanuele; Butler, D. Andre; Borders, Kevin L.; Stampahar, Jezabel; Schuck, William H.; Selfridge, Thomas L.; McKissack, Thomas M.; Duncan, William W.; Hendricks, Thane J.

    2012-10-17

    From 2007 to the present, the Remote Sensing Laboratory has been conducting a series of studies designed to expand our fundamental understanding of aerial neutron detection with the goal of designing an enhanced sensitivity detection system for long range neutron detection. Over 35 hours of aerial measurements in a helicopter were conducted for a variety of neutron emitters such as neutron point sources, a commercial nuclear power reactor, nuclear reactor spent fuel in dry cask storage, depleted uranium hexafluoride and depleted uranium metal. The goals of the project were to increase the detection sensitivity of our instruments such that a 5.4 × 104 neutron/second source could be detected at 100 feet above ground level at a speed of 70 knots and to enhance the long-range detection sensitivity for larger neutron sources, i.e., detection ranges above 1000 feet. In order to increase the sensitivity of aerial neutron detection instruments, it is important to understand the dynamics of the neutron background as a function of altitude. For aerial neutron detection, studies have shown that the neutron background primarily originates from above the aircraft, being produced in the upper atmosphere by galactic cosmic-ray interactions with air molecules. These interactions produce energetic neutrons and charged particles that cascade to the earth’s surface, producing additional neutrons in secondary collisions. Hence, the neutron background increases as a function of altitude which is an impediment to long-range neutron detection. In order to increase the sensitivity for long range detection, it is necessary to maintain a low neutron background as a function of altitude. Initial investigations show the variation in the neutron background can be decreased with the application of a cosmic-ray shield. The results of the studies along with a representative data set are presented.

  7. High-resolution inelastic neutron scattering and neutron powder diffraction study of the adsorption of dihydrogen by the Cu(II) metal–organic framework material HKUST-1

    Energy Technology Data Exchange (ETDEWEB)

    Callear, Samantha K.; Ramirez-Cuesta, Anibal J.; David, William I.F. [ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX (United Kingdom); Millange, Franck [Institut Lavoisier Versailles (CNRS UMR 8180), Université de Versailles, 78035 Versailles (France); Walton, Richard I., E-mail: r.i.walton@warwick.ac.uk [Department of Chemistry, University of Warwick, CV4 7AL, Coventry (United Kingdom)

    2013-12-12

    Highlights: • Binding sites for dihydrogen in a metal–organic framework have been identified. • The combination of diffraction and spectroscopy shows competitive filling of various adsorption sites. • Inelastic neutron scattering over wide-momentum transfer reveals new models for hydrogen-framework interactions. - Abstract: We present new high-resolution inelastic neutron scattering (INS) spectra (measured using the TOSCA and MARI instruments at ISIS) and powder neutron diffraction data (measured on the diffractometer WISH at ISIS) from the interaction of the prototypical metal–organic framework HKUST-1 with various dosages of dihydrogen gas. The INS spectra show direct evidence for the sequential occupation of various distinct sites for dihydrogen in the metal–organic framework, whose population is adjusted during increasing loading of the guest. The superior resolution of TOSCA reveals subtle features in the spectra, not previously reported, including evidence for split signals, while complementary spectra recorded on MARI present full information in energy and momentum transfer. The analysis of the powder neutron patterns using the Rietveld method shows a consistent picture, allowing the crystallographic indenisation of binding sites for dihydrogen, thus building a comprehensive picture of the interaction of the guest with the nanoporous host.

  8. Synthesis of specifically deuterated ceramide [AP]-C18 and its biophysical characterization using neutron diffraction.

    Science.gov (United States)

    Sonnenberger, Stefan; Eichner, Adina; Hauß, Thomas; Schroeter, Annett; Neubert, Reinhard H H; Dobner, Bodo

    2017-04-01

    The very heterogeneous group of ceramides is known to be mandatory for proper barrier functions of the outermost layer of mammalian skin, referred to as stratum corneum (SC). The synthesis of a specifically deuterated ceramide [AP]-C18 variant is described. The synthesized ceramide contains the racemic forms of the α hydroxy fatty acid. For the biophysical implementation, the received diastereomeric ceramide was applied in a neutron diffraction experiment. Therefore, a SC lipid model membrane was prepared containing the described ceramide (CER), cholesterol (CHOL), stearic acid (SA), and cholesterol sulfate (ChS) in a ratio of 55/25/15/5wt%. Thus, we were able to localize the deuterated molecule part within the bilayers. In the process, a short-periodicity phase (SPP) was observed with a unit cell scale of about 44Å. For the first time, we were able to confirm former ideas concerning the arrangement of the CER within this quaternary lipid model membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Magnetostructural phase transitions in NiO and MnO: Neutron diffraction data

    Science.gov (United States)

    Balagurov, A. M.; Bobrikov, I. A.; Sumnikov, S. V.; Yushankhai, V. Yu.; Mironova-Ulmane, N.

    2016-07-01

    Structural and magnetic phase transitions in NiO and MnO antiferromagnets have been studied by high-precision neutron diffraction. The experiments have been performed on a high-resolution Fourier diffractometer (pulsed reactor IBR-2), which has the record resolution for the interplanar distance and a high intensity in the region of large interplanar distances; as a result, the characteristics of both transitions have been determined simultaneously. It has been shown that the structural and magnetic transitions in MnO occur synchronously and their temperatures coincide within the experimental errors: T str ≈ T mag ≈ (119 ± 1) K. The measurements for NiO have been performed with powders with different average sizes of crystallites (~1500 nm and ~138 nm). It has been found that the transition temperatures differ by ~50 K: T str = (471 ± 3) K, T mag = (523 ± 2) K. It has been argued that a unified mechanism of the "unsplit" magnetic and structural phase transition at a temperature of T mag is implemented in MnO and NiO. Deviation from this scenario in the behavior of NiO is explained by the quantitative difference—a weak coupling between the magnetic and secondary structural order parameters.

  10. Distribution of Drug Molecules in Lipid Membranes: Neutron Diffraction and MD Simulations.

    Science.gov (United States)

    Boggara, Mohan; Mihailescu, Ella; Krishnamoorti, Ramanan

    2009-03-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) e.g. Aspirin and Ibuprofen, with chronic usage cause gastro intestinal (GI) toxicity. It has been shown experimentally that NSAIDs pre-associated with phospholipids reduce the GI toxicity and also increase the therapeutic activity of these drugs compared to the unmodified ones. In this study, using neutron diffraction, the DOPC lipid bilayer structure (with and without drug) as well as the distribution of a model NSAID (Ibuprofen) as a function of its position along the membrane normal was obtained at sub-nanometer resolution. It was found that the bilayer thickness reduces as the drug is added. Further, the results are successfully compared with atomistic Molecular Dynamics simulations. Based on this successful comparison and motivated by atomic details from MD, quasi-molecular modeling of the lipid membrane is being carried out and will be presented. The above study is expected to provide an effective methodology to design drug delivery nanoparticles based on a variety of soft condensed matter such as lipids or polymers.

  11. Understanding structural changes in NMC Li-ion cells by in situ neutron diffraction

    Science.gov (United States)

    Dolotko, O.; Senyshyn, A.; Mühlbauer, M. J.; Nikolowski, K.; Ehrenberg, H.

    2014-06-01

    Commercial NMC cells of 18650-type based on a Lix(Ni0.5Mn0.3Co0.2)O2 cathode and a graphitic anode were studied in situ using a combination of high-resolution monochromatic neutron powder diffraction and electrochemical analysis. The structural changes of the electrode materials during cell charge/discharge have been determined using Rietveld refinement and single profile decomposition techniques. A transformation of the graphitic anode to LiC12 and LiC6 through the formation of higher ordered lithium intercalated carbons was observed. A different behavior of electrochemically-driven lattice distortion was observed for NMC material in comparison to LixCoO2 and its influence on the overall cell performance has been discussed in brief. Detailed analysis of the structural changes in the Lix(Ni0.5Mn0.3Co0.2)O2 cathode material revealed reversible Li/Ni cation mixing (5.6(8)%), which is state-of-charge independent below 1600 mAh and vanishing above 1800 mAh (∼0.8Qmax).

  12. In situ observation of the formation of TiC from the elements by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Bjoern [Institut fuer Geowissenschaften, Abteilung Kristallographie, Universitaet Frankfurt, Senckenberganlage 30, D-60054 Frankfurt (Germany)]. E-mail: b.winkler@kristall.uni-frankfurt.de; Wilson, Dan J. [Institut fuer Geowissenschaften, Abteilung Kristallographie, Universitaet Frankfurt, Senckenberganlage 30, D-60054 Frankfurt (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Brown, Donald W. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sisneros, Thomas A. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Milman, Victor [Accelrys Inc., 334 Science Park, Cambridge CB4 0WN (United Kingdom)

    2007-08-30

    In situ neutron diffraction has been employed to investigate the formation of TiC{sub x} from the elements at relatively low temperatures, beginning at T{approx} 1073 deg. K. Slow heating of the mixture of the elements precludes the generation of sufficient heat to induce a self-propagating high temperature synthesis (SHS), reported in the literature for this system. We observe that the reaction starts well before the {alpha} -{beta} transition in Ti occurs, which implies that in this case this transition does not serve as a trigger mechanism for SHS. An extensive coexistence of both polymorphs of titanium suggests that a significant amount of carbon diffuses into the hexagonal {alpha}-Ti lattice and stabilizes it with respect to the cubic {beta}-phase. This is supported by the observation of an anomalous increase of the c-lattice parameter of the {alpha}-Ti lattice above the transition temperature for pure {alpha}-Ti. Density functional theory (DFT) based calculations support this interpretation. The energetics of the carburization of {alpha}-Ti have been obtained from the DFT calculations.

  13. Neutron diffraction of titanium aluminides formed by continuous electron-beam treatment

    Science.gov (United States)

    Valkov, S.; Neov, D.; Luytov, D.; Petrov, P.

    2016-03-01

    Ti-Al-based alloys were produced by hybrid electron-beam technologies. A composite Ti-Al film was deposited on a Ti substrate by electron-beam evaporation (EBE), followed by electron-beam treatment (EBT) by a continuously scanned electron beam. The speed of the specimens motion during the EBT were V 1 = 1 cm/sec and V 2 = 5 cm/sec, in order to realize two different alloying mechanisms -- by surface melting and by electron-beam irradiation without melting the surface. The samples prepared were characterized by XRD and neutron diffraction to study the crystal structure on the surface and in depth. SEM/EDX analysis was conducted to explore the surface structure and analyze the chemical composition. Nanoindentation measurements were also carried out. No intermetallic phases were registered in the sample treated at velocity V 1, while the sample treated at V 2 exhibited a Ti3Al/TiAl structure on the surface, transformed to Ti/TiAl in depth. The nanoindentation test demonstrated a significant negative hardness gradient from the surface to the depth of the sample.

  14. Spin and orbital ordering in TlMnO3: Neutron diffraction study

    Science.gov (United States)

    Khalyavin, Dmitry D.; Manuel, Pascal; Yi, Wei; Belik, Alexei A.

    2016-10-01

    Crystal and magnetic structures of the high-pressure stabilized perovskite phase of TlMnO3 have been studied by neutron powder diffraction. The crystal structure involves two types of primary structural distortions: a+b-b- octahedral tilting and antiferrodistortive type of orbital ordering, whose common action reduces the symmetry down to triclinic P 1 ¯ . The orbital pattern and the way it is combined with the octahedral tilting are different from the family of LnMnO3 (Ln = lanthanide or Y) manganites who share with TlMnO3 the same tilting scheme. The experimentally determined magnetic structure with the k =(1 /2 ,0 ,1 /2 ) propagation vector and PS1 ¯ symmetry implies anisotropic exchange interactions with a ferromagnetic coupling within the (1 ,0 ,1 ¯) planes and an antiferromagnetic one between them (A type). The spins in the primary magnetic mode were found to be confined close to the (1 ,0 ,1 ¯) plane, which underlines the predominant role of the single ion anisotropy with the local easy axes of Mn3 + following the Jahn-Teller distortions of the octahedra. In spite of the same octahedral tilting scheme in the perovskite structures of both LnMnO3 and TlMnO3 manganites, a coupling of the secondary ferromagnetic component to the primary A-type spin configuration through antisymmetric exchange interaction is allowed in the former and forbidden in the latter cases.

  15. A high-resolution neutron powder diffraction study of neodymium doping in barium cerate

    DEFF Research Database (Denmark)

    Knight, K.S.; Bonanos, N.

    1995-01-01

    in the thermal expansion properties are small in BaCe1-xNdxO3-x/2. The spontaneous strain decreases with increasing neodymium doping showing the deviation from an ideal cubic aristotype reduces with doping level. There is some evidence for saturation in the spontaneous strain at x>0.2.......High-resolution neutron powder diffraction data have been collected on 6 perovskites of composition BaCe1-xNdxO3-x/(2), with 0 less than or equal to x less than or equal to 0.2, in which structural phase transitions Pmcn-->P4/mbm at x=0.05, and P4/mbm-->Pm3m at x=0.1, were inferred from a recent...... Raman spectroscopy study. Our results contradict these conclusions; for 0 less than or equal to x less than or equal to 0.16, BaCe1-xNdxO3-x/2 is orthorhombic, space group Pmcn. At x=0.2, the powder data are consistent with either space group Pmcn or Cmcm, and could not be distinguished using structural...

  16. Thermal expansion and decomposition of jarosite: a high-temperature neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory; Hickmott, Donald D [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2009-01-01

    The structure of deuterated jarosite, KFe{sub 3}(SO{sub 4}){sub 2}(OD){sub 6}, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate {approx}10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH){sub 6}] octahedra and [SO{sub 4}] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, a = a{sub 0} + a{sub 1} T, where a{sub 0} = 1.01 x 10{sup -4} K{sup -1} and a{sub 1} = -1.15 x 10{sup -7} K{sup -2}. On heating, the hydrogen bonds, O1{hor_ellipsis}D-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D{hor_ellipsis}O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

  17. Collinear antiferromagnetism in trigonal SrMn2As2 revealed by single crystal neutron diffraction

    Science.gov (United States)

    Kreyssig, A.; Das, P.; Sangeetha, N. S.; Benson, Z. A.; Heitman, T.; Johnston, D. C.; Goldman, A. I.

    FeAs-based compounds and related materials have been an area of intense research in understanding the complex interplay between magnetism and superconductivity. Here we report on the magnetic structure of SrMn2As2 that crystallizes in a trigonal structure (P 3 m1) and undergoes an antiferromagnetic (AFM) transition at TN ~ 120 K. The temperature dependence of the magnetic susceptibility remains nearly constant below TN with H ∥ c while it decreases significantly with H ∥ ab . This shows that the local Mn moments order and lie in the ab plane instead of aligning along the c axis as in BaMn2As2. Single crystal neutron diffraction measurements on SrMn2As2 determined that the Mn moments are collinearly aligned in a G-type AFM order with AFM alignments between a moment and all nearest neighbors in the basal plane and also perpendicular to it. This manifests that G-type AFM order is robust for Mn122 systems despite different symmetries, i.e. tetragonal for BaMn2As2 and trigonal for SrMn2As2.Work at Ames Laboratory was supported by the DOE, BES, Division of Materials Sciences & Engineering, through DE-AC02-07CH11358. This research used resources at University of Missouri Research Reactor.

  18. Neutron diffraction study of MnNiGa{sub 2}—Structural and magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Ma, L.; Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Hofmann, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Avdeev, M.; Kennedy, S. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Md Din, M. F.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Hoelzel, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Fachbereich Materialwissenschaften, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2014-05-07

    MnNiGa{sub 2} crystallizes in the L21 (Heusler) structure and has a ferromagnetic ordering temperature T{sub C} ∼ 192 K. Rietveld refinement of the neutron diffraction patterns indicates that the Ga atoms occupy the equivalent 8c position, while Mn and Ni share the 4a (0, 0, 0) and 4b (0.5, 0.5, 0.5) sites with a mixed occupancy of Mn and Ni atoms. It is found that that ∼83% of Mn and ∼17% Ni are located at the 4a site while ∼83% of Ni and ∼17% Mn occupy the 4b site. There is no evidence of a magneto-volume effect around T{sub C}. In agreement with this finding, our detailed critical exponent analyses of isothermal magnetization curves and the related Arrott plots confirm that the magnetic phase transition at T{sub C} is second order.

  19. In situ observation of the reaction of scandium and carbon by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Juarez-Arellano, Erick A., E-mail: eajuarez@unpa.edu.m [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Universidad del Papaloapan, Circuito Central 200, Parque Industrial, Tuxtepec 68301 (Mexico); Winkler, Bjorn [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center. Mail Stop H805, Los Alamos, NM 87545 (United States); Senyshyn, Anatoliy [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, Lichtenbergstr. 1, D-85747 Garching (Germany); Materialwissenschaft, TU Darmstadt, Petersensstr. 23, D-64287 Darmstadt (Germany); Kammler, Daniel R. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Avalos-Borja, Miguel [CNyN, UNAM, A. Postal 2681, Ensenada, B.C. (Mexico)

    2011-01-05

    Research highlights: {yields} Exist two ScC cubic phases with B1-structure type differing in site occupancy of C. {yields} A new orthorhombic scandium carbide phase is formed at 1473(50) K. {yields} The recrystallization of alpha-Sc occurs between 1000 and 1223 K. - Abstract: The formation of scandium carbides by reaction of the elements has been investigated by in situ neutron diffraction up to 1823 K. On heating, the recrystallization of {alpha}-Sc occurs between 1000 and 1223 K. The formation of Sc{sub 2}C and ScC (NaCl-B1 type structure) phases has been detected at 1323 and 1373 K, respectively. The formation of a new orthorhombic scandium carbide phase was observed at 1473(50) K. Once the scandium carbides are formed they are stable upon heating or cooling. No other phases were detected in the present study, in which the system was always carbon saturated. The thermal expansion coefficients of all phases have been determined, they are constant throughout the temperature interval studied.

  20. Correlating cycling history with structural evolution in commercial 26650 batteries using in operando neutron powder diffraction

    Science.gov (United States)

    Goonetilleke, Damian; Pramudita, James C.; Hagan, Mackenzie; Al Bahri, Othman K.; Pang, Wei Kong; Peterson, Vanessa K.; Groot, Jens; Berg, Helena; Sharma, Neeraj

    2017-03-01

    Ex situ and time-resolved in operando neutron powder diffraction (NPD) has been used to study the structural evolution of the graphite negative electrode and LiFePO4 positive electrode within ANR26650M1A commercial batteries from A123 Systems, in what to our knowledge is the first reported NPD study investigating a 26650-type battery. Batteries with different and accurately-known electrochemical and storage histories were studied, enabling the tell-tale signs of battery degradation to be elucidated using NPD. The ex-situ NPD data revealed that the intensity of the graphite/lithiated graphite (LixC6 or LiyC) reflections was affected by battery history, with lower lithiated graphite (LiC12) reflection intensities typically corresponding to more abused batteries. This indicates that the lithiation of graphite is less progressed in more abused batteries, and hence these batteries have lower capacities. In operando NPD allows the rate of structural evolution in the battery electrode materials to be correlated to the applied current. Interestingly, the electrodes exhibit different responses to the applied current that depend on the battery cycling history, with this particularly evident for the negative electrode. Therefore, this work illustrates how NPD can be used to correlate a battery history with electrode structure.

  1. Neutron diffraction studies of the interaction between amphotericin B and lipid-sterol model membranes

    Science.gov (United States)

    Foglia, Fabrizia; Lawrence, M. Jayne; Demeė, Bruno; Fragneto, Giovanna; Barlow, David

    2012-10-01

    Over the last 50 years or so, amphotericin has been widely employed in treating life-threatening systemic fungal infections. Its usefulness in the clinic, however, has always been circumscribed by its dose-limiting side-effects, and it is also now compromised by an increasing incidence of pathogen resistance. Combating these problems through development of new anti-fungal agents requires detailed knowledge of the drug's molecular mechanism, but unfortunately this is far from clear. Neutron diffraction studies of the drug's incorporation within lipid-sterol membranes have here been performed to shed light on this problem. The drug is shown to disturb the structures of both fungal and mammalian membranes, and co-localises with the membrane sterols in a manner consistent with trans-membrane pore formation. The differences seen in the membrane lipid ordering and in the distributions of the drug-ergosterol and drug-cholesterol complexes within the membranes are consistent with the drug's selectivity for fungal vs. human cells.

  2. Neutron diffraction studies of magnetic ordering in Ni-doped LaCoO3

    Science.gov (United States)

    Rajeevan, N. E.; Kumar, Vinod; Kumar, Rajesh; Kumar, Ravi; Kaushik, S. D.

    2015-11-01

    Research in rare earth cobaltite has recently been intensified due to its fascinating magnetic properties. LaCoO3, an important cobaltite, exhibits two prominent susceptibility features at ~90 K and 500 K in low field measurement. The magnetic behavior below 100 K is predominantly antiferromagnetic (AFM), but absence of pure AFM ordering and emergence of ferromagnetic coupling on further decreasing temperature made situation more intricate. The present work of studying the effect of Ni substitution at Co site in polycrystalline LaCo1-xNixO3 (0≤x≤0.3) is motivated by the interesting changes in magnetic and electronic properties. For lucid understanding, temperature dependent neutron diffraction (ND) study was carried out. ND patterns fitted with rhombohedral structure in perovskite form with R-3c space group, elucidated information on phase purity. Further temperature dependent cell parameter, Co-O bond-length and Co-O-Co bond angle were calculated for the series of Ni doped LaCoO3. The results are explained in terms of decrease in the crystal field energy which led to the transition of cobalt from low Spin (LS) state to intermediate spin state (IS).

  3. In Situ Neutron Diffraction Studies of Large Monotonic Deformations of Superelastic Nitinol

    Science.gov (United States)

    Stebner, Aaron P.; Paranjape, Harshad M.; Clausen, Bjørn; Brinson, L. Catherine; Pelton, Alan R.

    2015-06-01

    Superelastic Nitinol micromechanics are studied well into plastic deformation regimes using neutron diffraction. Insights are made into the nature of initial transformation, bulk transformation, plastic deformation, and unloading. Schmid factor predictions based on habit plane variants are found to best describe the very first grains that transform, prior to the transformation plateaus. However, the bulk transformation behavior that gives rise to transformation plateaus violates single crystal Schmid factor analyses, indicating that in bulk polycrystals, it is the effect of grain neighborhoods, not the orientations of individual grains, that drives transformation behaviors. Beyond the plateaus, a sudden shift in micromechanical deformation mechanisms is observed at ~8.50 %/4.75 % tension/compression engineering strain. This mechanism results in reverse-phase transformation in both cases, indicating a strong relaxation in internal stresses of the samples. It is inferred that this mechanism is most likely initial bulk plastic flow, and postulated that it is the reason for a transition from fatigue life enhancement to detriment when pre-straining superelastic Nitinol. The data presented in this work provide critical datasets for development and verification of both phenomenological internal variable-driven and micromechanical theories of transformation-plasticity coupling in shape memory alloys.

  4. Use of a miniature diamond-anvil cell in high-pressure single-crystal neutron Laue diffraction

    Directory of Open Access Journals (Sweden)

    Jack Binns

    2016-05-01

    Full Text Available The first high-pressure neutron diffraction study in a miniature diamond-anvil cell of a single crystal of size typical for X-ray diffraction is reported. This is made possible by modern Laue diffraction using a large solid-angle image-plate detector. An unexpected finding is that even reflections whose diffracted beams pass through the cell body are reliably observed, albeit with some attenuation. The cell body does limit the range of usable incident angles, but the crystallographic completeness for a high-symmetry unit cell is only slightly less than for a data collection without the cell. Data collections for two sizes of hexamine single crystals, with and without the pressure cell, and at 300 and 150 K, show that sample size and temperature are the most important factors that influence data quality. Despite the smaller crystal size and dominant parasitic scattering from the diamond-anvil cell, the data collected allow a full anisotropic refinement of hexamine with bond lengths and angles that agree with literature data within experimental error. This technique is shown to be suitable for low-symmetry crystals, and in these cases the transmission of diffracted beams through the cell body results in much higher completeness values than are possible with X-rays. The way is now open for joint X-ray and neutron studies on the same sample under identical conditions.

  5. Neutron Diffraction Studies of the Atomic Vibrations of Bulk and Surface Atoms of Nanocrystalline SiC

    Science.gov (United States)

    Stelmakh, S.; Grzanka, E.; Zhao, Y.; Palosz, W.; Palosz, B.

    2004-01-01

    Thermal atomic motions of nanocrystalline Sic were characterized by two temperature atomic factors B(sub core), and B(sub shell). With the use of wide angle neutron diffraction data it was shown that at the diffraction vector above 15A(exp -1) the Wilson plots gives directly the temperature factor of the grain interior (B(sub core)). At lower Q values the slope of the Wilson plot provides information on the relative amplitudes of vibrations of the core and shell atoms.

  6. Neutron diffraction study of nanocrystalline NbC0.93 powders and the anisotropy of deformation distortions

    Science.gov (United States)

    Kurlov, A. S.; Bobrikov, I. A.; Balagurov, A. M.; Gusev, A. I.

    2015-01-01

    Broadening of the diffraction reflections in nanocrystalline powders of nonstoichiometric niobium carbide NbC0.93 with the average particle size from ˜200 to ˜2000 Å has been studied by the neutron diffraction method. The functional dependence of the broadening W 2 on the interplanar distance d 2 has been obtained including size, deformation, and inhomogeneous broadening. The average size of the coherent scattering regions and microstrains in crystallites with allowance for the anisotropy of the deformation distortions have been estimated.

  7. Production and applications of neutrons using particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Chichester, David L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2009-11-01

    Advances in neutron science have gone hand in hand with the development and of particle accelerators from the beginning of both fields of study. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and how neutrons interact in matter, but people quickly realized that more tangible uses existed too. Today the diversity of applications for industrial accelerator-based neutron sources is high and so to is the actual number of instruments in daily use is high, and they serve important roles in the fields where they're used. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the early development of neutron-producing particle accelerators, a description of some current industrial accelerator systems, narratives of the fields where neutron-producing particle accelerators are used today, and comments on future trends in the industrial uses of neutron producing particle accelerators.

  8. PRODUCTION AND APPLICATIONS OF NEUTRONS USING PARTICLE ACCELERATORS

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester

    2009-11-01

    Advances in neutron science have gone hand in hand with the development and of particle accelerators from the beginning of both fields of study. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and how neutrons interact in matter, but people quickly realized that more tangible uses existed too. Today the diversity of applications for industrial accelerator-based neutron sources is high and so to is the actual number of instruments in daily use is high, and they serve important roles in the fields where they're used. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the early development of neutron-producing particle accelerators, a description of some current industrial accelerator systems, narratives of the fields where neutron-producing particle accelerators are used today, and comments on future trends in the industrial uses of neutron producing particle accelerators.

  9. Energy-dispersive neutron imaging and diffraction of magnetically driven twins in a Ni2MnGa single crystal magnetic shape memory alloy

    Science.gov (United States)

    Kabra, Saurabh; Kelleher, Joe; Kockelmann, Winfried; Gutmann, Matthias; Tremsin, Anton

    2016-09-01

    Single crystals of a partially twinned magnetic shape memory alloy, Ni2MnGa, were imaged using neutron diffraction and energy-resolved imaging techniques at the ISIS spallation neutron source. Single crystal neutron diffraction showed that the crystal produces two twin variants with a specific crystallographic relationship. Transmission images were captured using a time of flight MCP/Timepix neutron counting detector. The twinned and untwinned regions were clearly distinguishable in images corresponding to narrow-energy transmission images. Further, the spatially-resolved transmission spectra were used to elucidate the orientations of the crystallites in the different volumes of the crystal.

  10. Investigation on the Residual Stress State of Drawn Tubes by Numerical Simulation and Neutron Diffraction Analysis

    Directory of Open Access Journals (Sweden)

    Adele Carradò

    2013-11-01

    Full Text Available Cold drawing is widely applied in the industrial production of seamless tubes, employed for various mechanical applications. During pre-processing, deviations in tools and their adjustment lead to inhomogeneities in the geometry of the tubes and cause a gradient in residuals. In this paper a three dimensional finite element (3D-FE-model is presented which was developed to calculate the change in wall thickness, eccentricity, ovality and residual macro-stress state of the tubes, produced by cold drawing. The model simulates the drawing process of tubes, drawn with and without a plug. For finite element modelling, the commercial software package Abaqus was used. To validate the model, neutron strain imaging measurements were performed on the strain imaging instrument SALSA at the Institute Laue Langevin (ILL, Grenoble, France on a series of SF-copper tubes, drawn under controlled laboratory conditions, varying the drawing angle and the plug geometry. It can be stated that there is sufficient agreement between the finite element method (FEM-calculation and the neutron stress determination.

  11. High-resolution neutron diffraction study of CuNCN: new evidence of structure anomalies at low temperature.

    Science.gov (United States)

    Jacobs, Philipp; Houben, Andreas; Tchougréeff, Andrei L; Dronskowski, Richard

    2013-12-14

    Copper carbodiimide (CuNCN) is the nitrogen-containing analogue of cupric oxide. Based on high-resolution neutron-diffraction data, CuNCN's lattice parameters are derived as a function of the temperature. In accordance with a recent synchrotron study, a clear trend in the cell parameter a is observed accompanying the changing magnetic behavior. With decreasing temperature, a slowly decreases to a minimum at ~100 K after which it rises again. The same trend-albeit more pronounced-is observed for the c lattice parameter at ~35 K. The herein presented neutron powder-diffraction data also support the conjectured sequence of transitions from the high-temperature one-dimensional resonating valence-bond (RVB) state to a transient two-dimensional RVB state and eventually, at lowest temperatures, into another two-dimensional RVB state, presumably the ground state.

  12. Neutron diffraction and electrical transport studies on the incommensurate magnetic phase transition in holmium at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Sarah [University of Alabama, Birmingham; Uhoya, Walter [University of Alabama, Birmingham; Tsoi, Georgiy [University of Alabama, Birmingham; Wenger, Lowell E [University of Alabama, Birmingham; Vohra, Yogesh [University of Alabama, Birmingham; Chesnut, Gary Neal [University of Alabama, Birmingham; Weir, S. T. [Lawrence Livermore National Laboratory (LLNL); Tulk, Christopher A [ORNL; Moreira Dos Santos, Antonio F [ORNL

    2012-01-01

    Neutron diffraction and electrical transport measurements have been made on the heavy rare earth metal holmium at high pressures and low temperatures in order to elucidate its transition from a paramagnetic (PM) to a helical antiferromagnetic (AFM) ordered phase as a function of pressure. The electrical resistance measurements show a change in the resistance slope as the temperature is lowered through the antiferromagnetic Neel temperature. The temperature of this antiferromagnetic transition decreases from approximately 122 K at ambient pressure at a rate of -4.9 K GPa(-1) up to a pressure of 9 GPa, whereupon the PM-to-AFM transition vanishes for higher pressures. Neutron diffraction measurements as a function of pressure at 89 and 110 K confirm the incommensurate nature of the phase transition associated with the antiferromagnetic ordering of the magnetic moments in a helical arrangement and that the ordering occurs at similar pressures as determined from the resistance results for these temperatures.

  13. Crystalline, mixed-valence manganese analogue of prussian blue: magnetic, spectroscopic, X-ray and neutron diffraction studies.

    Science.gov (United States)

    Franz, Patrick; Ambrus, Christina; Hauser, Andreas; Chernyshov, Dmitry; Hostettler, Marc; Hauser, Jürg; Keller, Lukas; Krämer, Karl; Stoeckli-Evans, Helen; Pattison, Philip; Bürgi, Hans-Beat; Decurtins, Silvio

    2004-12-22

    The compound of stoichiometry Mn(II)3[Mn(III)(CN)6]2.zH2O (z = 12-16) (1) forms air-stable, transparent red crystals. Low-temperature single crystal optical spectroscopy and single crystal X-ray diffraction provide compelling evidence for N-bonded high-spin manganese(II), and C-bonded low-spin manganese(III) ions arranged in a disordered, face-centered cubic lattice analogous to that of Prussian Blue. X-ray and neutron diffraction show structured diffuse scattering indicative of partially correlated (rather than random) substitutions of [Mn(III)(CN)6] ions by (H2O)6 clusters. Magnetic susceptibility measurements and elastic neutron scattering experiments indicate a ferrimagnetic structure below the critical temperature Tc = 35.5 K.

  14. Fluid bilayer structure determination: Joint refinement in composition space using X-ray and neutron diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    White, S.H. [Univ. of California, Irvine, CA (United States); Wiener, M.C. [Univ. of California, San Francisco, CA (United States)

    1994-12-31

    Experimentally-determined structural models of fluid lipid bilayers are essential for verifying molecular dynamics simulations of bilayers and for understanding the structural consequences of peptide interactions. The extreme thermal motion of bilayers precludes the possibility of atomic-level structural models. Defining {open_quote}the structure{close_quote} of a bilayer as the time-averaged transbilayer distribution of the water and the principal lipid structural groups such as the carbonyls and double-bonds (quasimolecular fragments), one can represent the bilayer structure as a sum of Gaussian functions referred to collectively as the quasimolecular structure. One method of determining the structure is by neutron diffraction combined with exhaustive specific deuteration. This method is impractical because of the expense of the chemical syntheses and the limited amount of neutron beam time currently available. We have therefore developed the composition space refinement method for combining X-ray and minimal neutron diffraction data to arrive at remarkably detailed and accurate structures of fluid bilayers. The composition space representation of the bilayer describes the probability of occupancy per unit length across the width of the bilayer of each quasimolecular component and permits the joint refinement of X-ray and neutron lamellar diffraction data by means of a single quasimolecular structure that is fitted simultaneously to both data sets. Scaling of each component by the appropriate neutron or X-ray scattering length maps the composition-space profile to the appropriate scattering length space for comparison to experimental data. The difficulty with the method is that fluid bilayer structures are generally only marginally determined by the experimental data. This means that the space of possible solutions must be extensively explored in conjunction with a thorough analysis of errors.

  15. The role of iron in tetrahedrite and tennantite determined by Rietveld refinement of neutron powder diffraction data

    DEFF Research Database (Denmark)

    Andreasen, Jens Wenzel; Makovicky, Emil; Lebech, Bente

    2008-01-01

    Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12-xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12-xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated...

  16. Neutron diffraction and Moessbauer study on FeGa{sub x}Cr{sub 2-x}S{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sam Jin; Son, Bae Soon; Shim, In-Bo [Kookmin University, Department of Physics (Korea, Republic of); Lee, Bo Wha [Hankuk University of Foreign Studies, Department of Physics (Korea, Republic of); Kim, Chul Sung, E-mail: cskim@phys.kookmin.ac.kr [Kookmin University, Department of Physics (Korea, Republic of)

    2006-02-15

    Ga doped sulphur spinel FeGa{sub x}Cr{sub 2-x}S{sub 4} (x = 0.1 and 0.3) have been studied with X-ray, neutron diffraction, and Moessbauer spectroscopy. Rietveld refinement of X-ray, neutron diffraction, and Moessbauer spectroscopy lead to the conclusion that the samples are in inverse spinel type, where most Ga ions are present at octahedral site (B). The neutron diffractions on FeGa{sub x}Cr{sub 2-x}S{sub 4} (x = 0.1) above 10 K show long range interaction behaviors and reveal a ferrimagnetic ordering, with the magnetic moment of Fe{sup 2+}(-3.45 {mu}{sub B}) aligned antiparallel to Cr{sup 3+} (+2.89 {mu}{sub B}) at 10 K. Fe ions migrate from the tetrahedral (A) site to the octahedral (B) site with an increase in Ga substitutions. The electric quadrupole splittings of the A and B sites in Moessbauer spectra give direct evidence that Ga ions stimulate an asymmetric charge distribution of Fe ions in the A site.

  17. Investigation of an unusual low-temperature phase transformation in RbBH{sub 4} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kitchen, Brian B. [Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Verdal, Nina, E-mail: nina.verdal@nist.gov [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Udovic, Terrence J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Rush, John J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Hartman, Michael R. [Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); DeVries, Daniel J. [Radiation and Isotopes for Health, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

    2013-07-15

    To investigate the previously reported low-temperature phase transition in rubidium borohydride (RbBH{sub 4}) near 48.5 K, we carried out neutron powder diffraction and vibrational spectroscopy measurements both above and below this temperature on an isotopically-enriched sample of Rb{sup 11}BD{sub 4}. Our diffraction data reflected an average cubic Fm3{sup ¯}m structure with BD{sub 4}{sup −} anion orientational disorder at all temperatures, with no hint of extra Bragg peaks due to long-range orientational order below the transition temperature as reported by others. These structural results and careful analysis of torsional vibrations in RbBD{sub 4} corroborate the results of prior neutron vibrational spectroscopy measurements suggesting that the low-temperature RbBH{sub 4} structure indeed possesses some orientational ordering of the BH{sub 4}{sup −} anions, but of a shorter-ranged nature insensitive to powder diffraction methods. - The neutron powder diffraction pattern of RbBD{sub 4} below the phase transition temperature (shown here in black) is indistinguishable from that collected above the phase transition temperature. The inset depicts the cubic structure that fits the data at both temperatures. - Highlights: • We investigated the nature of the RbBD{sub 4} phase transition using NVS and NPD. • A change in shape of the RbBD{sub 4} torsion mode was observed across the transition. • The RbBD{sub 4} diffraction pattern across this phase transition was unchanged. • The phase transition in RbBD{sub 4} appears to produce only short-range ordering of BD{sub 4}{sup −}.

  18. Antiferroelastic structural transitions in PrAlO{sub 3} by means of neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S. [Department of Physics, Graduate School of Sciences, Kyushu University, 33, Fukuoka 812-8581 (Japan); Neutron Scattering Laboratory, ISSP, University of Tokyo, Tokai, Ibaraki, 319-1106 (Japan); Hidaka, M. [Department of Physics, Graduate School of Sciences, Kyushu University, 33, Fukuoka 812-8581 (Japan); Yoshizawa, H. [Neutron Scattering Laboratory, ISSP, University of Tokyo, Tokai, Ibaraki, 319-1106 (Japan); Wanklyn, B.M. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU (United Kingdom)

    2006-02-01

    Structural phase transitions of the perovskite-type PrAlO{sub 3} have been studied by using neutron diffraction. The results show that, on cooling, the structures are successively transformed from R anti 3c (Phase II) to Imma (Phase III), Imma (Phase IV), I4/mcm (Phase V) by the 215-K, 153-K, and 122-K transitions. The tilting schemes in Phase III, IV and V are mainly characterized by ({psi}{sub a} = {psi}{sub c}, {psi}{sub b} = 0), ({psi}{sub a} {ne} {psi}{sub c}, {psi}{sub b} = 0), and ({psi}{sub c}, {psi}{sub a} = {psi}{sub b} = 0), respectively, where {psi}{sub a}, {psi}{sub b} and {psi}{sub c} are rotational angles around a-, b-, and c-primitive axes of the AlO{sub 6} octahedron. The refreezes of the condensed R{sub 25} {sub {sup y}} and R {sub 25} {sub {sup x}} optical soft modes occurring at about 215 K and 122 K are interpreted by correlation with the cooperative Jahn-Teller distortion (JTD) of the Pr {sup 3+}-4f orbitals in the PrO {sub 12} polyhedra. The phase IV is characterized as an intermediate state, in which the {psi}{sub a} tilts are continuously reduced by the JTD and disappear just above the 122-K transition. The easy mobility of the domain walls suggests the PrAlO {sub 3} crystal to be of antiferroelastic nature, an unusual property that results from the cooperative displacements of O ions induced by the correlation between the antiphase tilts along primitive axes of the AlO {sub 6} octahedra and the JTD around Pr {sup +3} ions in PrO {sub 12} polyhedra. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Single crystal polarized neutron diffraction study of the magnetic structure of HoFeO3.

    Science.gov (United States)

    Chatterji, T; Stunault, A; Brown, P J

    2017-07-05

    Polarised neutron diffraction measurements have been made on HoFeO3 single crystals magnetised in both the [0 0 1] and [1 0 0] directions (Pbnm setting). The polarisation dependencies of Bragg reflection intensities were measured both with a high field of [Formula: see text] T parallel to [0 0 1] at [Formula: see text] K and with the lower field [Formula: see text] T parallel to [1 0 0] at [Formula: see text] K. A Fourier projection of magnetization induced parallel to [0 0 1], made using the hk0 reflections measured in 9 T, indicates that almost all of it is due to alignment of Ho moments. Further analysis of the asymmetries of general reflections in these data showed that although, at 70 K, 9 T applied parallel to [0 0 1] hardly perturbs the antiferromagnetic order of the Fe sublattices, it induces significant antiferromagnetic order of the Ho sublattices in the [Formula: see text] plane, with the antiferromagnetic components of moment having the same order of magnitude as the induced ferromagnetic ones. Strong intensity asymmetries measured in the low temperature [Formula: see text] structure with a lower field, 0.5 T [Formula: see text] [1 0 0] allowed the variation of the ordered components of the Ho and Fe moments to be followed. Their absolute orientations, in the [Formula: see text] domain stabilised by the field were determined relative to the distorted perovskite structure. This relationship fixes the sign of the Dzyalshinski-Moriya (D-M) interaction which leads to the weak ferromagnetism. Our results indicate that the combination of strong y-axis anisotropy of the Ho moments and Ho-Fe exchange interactions breaks the centrosymmetry of the structure and could lead to ferroelectric polarization.

  20. An in situ Study of NiTi Powder Sintering Using Neutron Diffraction

    Directory of Open Access Journals (Sweden)

    Gang Chen

    2015-04-01

    Full Text Available This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2 by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of 1373 K. The phase evolution was performed by in situ neutron diffraction upon sintering and cooling. The predominant phase identified in all the produced porous NiTi alloys after being sintered at 1373 K is B2 NiTi phase with the presence of other minor phases. It is found that dehydrogenation of TiH2 significantly affects the sintering behavior and resultant microstructure. In comparison to the Ni/Ti compact, dehydrogenation occurring in the Ni/TiH2 compact leads to less densification, yet higher chemical homogenization, after high temperature sintering but not in the case of low temperature sintering. Moreover, there is a direct evidence of the eutectoid decomposition of NiTi at ca. 847 and 823 K for Ni/Ti and Ni/TiH2, respectively, during furnace cooling. The static and cyclic stress-strain behaviors of the porous NiTi alloys made from the Ni/Ti and Ni/TiH2 compacts were also investigated. As compared with the Ni/Ti sintered samples, the samplessintered from the Ni/TiH2 compact exhibited a much higher porosity, a higher close-to-total porosity, a larger pore size and lower tensile and compressive fracture strength.

  1. Neutron diffraction studies of nanoparticle RMnO{sub 3} compounds (R=Pr, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Baran, S., E-mail: stanislaw.baran@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland); Dyakonov, V. [Institute of Physics, PAS, Al. Lotników 32/46, PL-02-668 Warszawa (Poland); A. A. Gałkin Donetsk Physico-Technical Institute, National Academy of Sciences of Ukraine, 72 R. Luxembourg Str., Donetsk 83114 (Ukraine); Hofmann, T.; Hoser, A. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, D-14 109 Berlin (Germany); Penc, B. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland); Kravchenko, Z. [A. A. Gałkin Donetsk Physico-Technical Institute, National Academy of Sciences of Ukraine, 72 R. Luxembourg Str., Donetsk 83114 (Ukraine); Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland)

    2013-10-15

    The neutron diffraction measurements of the nano-size RMnO{sub 3} (R=Pr, Nd) manganites have been performed. The obtained results indicate that these compounds crystallize in the orthorhombic crystal structure described by the space group Pnma. Low temperature data indicate both the absence of a long-range magnetic order down to 1.5 K in the PrMnO{sub 3} sample annealed at 800 °C and the C{sub x}F{sub y} magnetic structure with a very low value of the Mn magnetic moment as compared with bulk sample in the sample annealed at 900 °C. In the NdMnO{sub 3} samples annealed at 850 °C and 900 °C the magnetic order is described by the C{sub x}F{sub y} mode in the Mn sublattice and the F{sub y} mode in the Nd sublattice. The values of the Mn and Nd magnetic moments are lower that those in a bulk sample. Based on the model proposed in López-Quintela et al. [1] and Balcells et al. [2] the thickness of nonmagnetic shell was determined to be 7.1(4) nm in PrMnO{sub 3} and 4.6(5) nm in both the NdMnO{sub 3} compounds. - Highlights: • Magnetic structures of nanoparticle RMnO{sub 3} (R = Pr, Nd) samples have been determined. • The results have been compared with those obtained for polycrystalline samples. • According to the model in Refs. [1,2] the thickness of nonmagnetic shell has been found.

  2. Neutron Diffraction of Aqueous Tetramethylammonium Chloride (TMA) Solutions and TMA Intercalated Swelling Clays Under Burial Conditions

    Science.gov (United States)

    Patel, R.; Howard, C. A.; Greenwell, C.; Youngs, T.; Soper, A. K.; Skipper, N. T.

    2014-12-01

    There is a need for the improvement and optimisation of clay swelling inhibitors for the enhancement of oil and gas exploration. The hydration region of both ions and the possibility of ion pairing in 1 molar aqueous solution of clay swelling inhibitor, tetramethylammonium chloride (TMACl), in D2O, under elevated hydrostatic-pressures and temperatures has been determined with unprecedented detail using a combination of neutron diffraction and small-angle scattering in conjunction with hydrogen/deuterium isotopic labeling. The O-H correlation function (H-bonds) for the water in the 1.0M solution is measured and compared with that for pure D2O. Also investigated is the effect of burial conditions on the d-spacing of TMA-intercalated vermiculite. Contrary to expectations, no aggregation of TMA ions due to hydrophobic interactions is observed, nor are any ionic pairs of TMA+ and Cl- at these burial conditions. The data revealed a more ordered water-water structure with the addition of TMACl from bulk D2O. There is no change in the hydration structure measured at the applied elevated conditions. This is in remarkable contrast to pure water at the same conditions which is well known to be compressible. The dry d-spacing of the TMA-exchanged Eucatex vermiculite is measured at 13.66 Å which increases to 14.03 Å with the addition of D2O. Beyond this, there is no change in d-spacing with increasing pressure and temperature indicating the strength of the TMA ions binding to the clay interlayers and therefore its performance as a clay-swelling inhibitor.

  3. Elements of slow-neutron scattering basics, techniques, and applications

    CERN Document Server

    Carpenter, J M

    2015-01-01

    Providing a comprehensive and up-to-date introduction to the theory and applications of slow-neutron scattering, this detailed book equips readers with the fundamental principles of neutron studies, including the background and evolving development of neutron sources, facility design, neutron scattering instrumentation and techniques, and applications in materials phenomena. Drawing on the authors' extensive experience in this field, this text explores the implications of slow-neutron research in greater depth and breadth than ever before in an accessible yet rigorous manner suitable for both students and researchers in the fields of physics, biology, and materials engineering. Through pedagogical examples and in-depth discussion, readers will be able to grasp the full scope of the field of neutron scattering, from theoretical background through to practical, scientific applications.

  4. X-ray and neutron diffraction measurements of dislocation density and subgrain size in a friction stir welded aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Claussen, Bjorn [Los Alamos National Laboratory; Woo, Wanchuck [ORNL; Zhili, Feng [ORNL; Edward, Kenik [ORNL; Ungar, Tamas [EOTVOS UNIV.

    2009-01-01

    The dislocation density and subgrain size were determined in the base material and friction-stir welds of 6061-T6 aluminum alloy. High-resolution X-ray diffraction measurement was performed in the base material. The result of the line profile analysis of the X-ray diffraction peak shows that the dislocation density is about 4.5 x 10{sup 14} m{sup 02} and the subgrain size is about 200 nm. Meanwhile, neutron diffraction measurements have been performed to observe the diffraction peaks during friction-stir welding (FSW). The deep penetration capability of the neutron enables us to measure the peaks from the midplane of the Al plate underneath the tool shoulder of the friction-stir welds. The peak broadening analysis result using the Williamson-Hall method shows the dislocation density of about 3.2 x 10{sup 15} m{sup -2} and subgrain size of about 160 nm. The significant increase of the dislocation density is likely due to the severe plastic deformation during FSW. This study provides an insight into understanding the transient behavior of the microstructure under severe thermomechanical deformation.

  5. Structure of Se-Te glasses studied using neutron, X-ray diffraction and reverse Monte Carlo modelling

    Science.gov (United States)

    Itoh, Keiji

    2017-02-01

    Pulsed neutron diffraction and synchrotron X-ray diffraction measurements were performed on Se100-xTex bulk glasses with x=10, 20, 30 and 40. The coordination numbers obtained from the diffraction results demonstrate that Se and Te atoms are twofold coordinated and the glass structure is formed by the chain network. The three-dimensional structure model for Se60Te40 glass obtained by using reverse Monte Carlo modelling shows that the alternating arrangements of Se and Te atoms compose the major part of the chain clusters but several other fragments such as Sen chains and Te-Te dimers are also present in large numbers. The chain clusters have geometrically disordered forms and the interchain atomic order is different from those in the crystal structures of trigonal Se and trigonal Te.

  6. Behavior of H(sub2)O and OH in lawsonite : a single crystal neutron diffraction and Raman spectroscopic investigation.

    Energy Technology Data Exchange (ETDEWEB)

    Kolesov, B. A.; Lager, G. A.; Schultz, A. J.; Russian Academy of Science; Univ. of Louisville

    2008-01-01

    Neutron diffraction and polarized single-crystal Raman spectroscopic measurements were made on the high-pressure silicate lawsonite, CaAl{sub 2}(Si{sub 2}O{sub 7})(OH){sub 2} {center_dot} H{sub 2}O, from Tiburon Peninsula, California. For the diffraction measurements, intensity reflection data were collected at temperatures of 295, 110 and 20 K using time-of-flight neutron diffraction methods to further examine two reversible, order-disorder type phase transitions occurring at 273 and 155 K [Cmcm (> 273 K) {yields} Pmcn (< 273 K) {yields} P2{sub 1}cn (< 155 K)]. These data are also used to model the H atom displacements in lawsonite as a function of temperature and to provide better insight into the nature of H bonding. The Raman spectroscopic measurements (2500 to 4000 cm{sup -1} at 4 {ge} T {ge} 300 K) were carried out on the same crystal used for the neutron diffraction study. Four OH-related bands are observed between 2700 and 3600 cm{sup -1}. The OH groups and H{sub 2}O molecules, which are linked by hydrogen bonding, build quasi one-dimensional chains in lawsonite, that run parallel to [001] and thus a model consisting of isolated oscillators cannot be used to interpret the spectra at ambient temperature. A notable feature of spectral behavior at 240-260 K in the vicinity of the Cmcm {leftrightarrow} Pmcn phase transition is the change-over of strong hydrogen bonding from the OH group to the H{sub 2}O molecule. The lowest-wavenumber OH(H{sub 2}O) band at 2780 cm{sup -1} at 4 K is broad and asymmetric, which is related to strong hydrogen bonding, and is characterized by strong anharmonicity. This band was deconvoluted into a number of combination modes consisting of an internal-H{sub 2}O and various external-H{sub 2}O vibrations.

  7. Spinel materials for Li-ion batteries: new insights obtained by operando neutron and synchrotron X-ray diffraction.

    Science.gov (United States)

    Bianchini, Matteo; Fauth, François; Suard, Emmanuelle; Leriche, Jean Bernard; Masquelier, Christian; Croguennec, Laurence

    2015-12-01

    In the last few decades Li-ion batteries changed the way we store energy, becoming a key element of our everyday life. Their continuous improvement is tightly bound to the understanding of lithium (de)intercalation phenomena in electrode materials. Here we address the use of operando diffraction techniques to understand these mechanisms. We focus on powerful probes such as neutrons and synchrotron X-ray radiation, which have become increasingly familiar to the electrochemical community. After discussing the general benefits (and drawbacks) of these characterization techniques and the work of customization required to adapt standard electrochemical cells to an operando diffraction experiment, we highlight several very recent results. We concentrate on important electrode materials such as the spinels Li1 + xMn2 - xO4 (0 ≤ x ≤ 0.10) and LiNi0.4Mn1.6O4. Thorough investigations led by operando neutron powder diffraction demonstrated that neutrons are highly sensitive to structural parameters that cannot be captured by other means (for example, atomic Debye-Waller factors and lithium site occupancy). Synchrotron radiation X-ray powder diffraction reveals how LiMn2O4 is subject to irreversibility upon the first electrochemical cycle, resulting in severe Bragg peak broadening. Even more interestingly, we show for the first time an ordering scheme of the elusive composition Li0.5Mn2O4, through the coexistence of Mn(3+):Mn(4+) 1:3 cation ordering and lithium/vacancy ordering. More accurately written as Li0.5Mn(3+)0.5Mn(4+)1.5O4, this intermediate phase loses the Fd\\overline 3m symmetry, to be correctly described in the P213 space group.

  8. Modulation spectrometry of neutrons with diffractometry applications

    CERN Document Server

    Hiismäki, Pekka

    1997-01-01

    Modulation spectrometry of neutrons refers to a measuring principle, characterized by classification of neutron histories in a probabilistic way, not the usual deterministic way. In order to accomplish this, neutron beams entering the sample are modulated by high-transmission, white-beam selectors of the multislit type, such as Fourier or statistical choppers or high-frequency-modulated spin-flippers. In this scheme it is impossible to decide in a unique way through which particular slit any single neutron passed, but the distribution of histories for a large population of neutrons can neverth

  9. Magnetic ordering of ScMn{sub 6}Ge{sub 6} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Schobinger-Papamantellos, P., E-mail: Schobinger@mat.ethz.ch [Laboratory of Crystallography, ETH-Zürich, 8093 Zürich (Switzerland); Rodríguez-Carvajal, J. [Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex (France); Buschow, K.H.J. [Van der Waals-Zeeman Institute, University of Amsterdam, NL-1018 XE The Netherlands (Netherlands)

    2014-11-15

    The compound ScMn{sub 6}Ge{sub 6} (HfFe{sub 6}Ge{sub 6}-type, P6/mmm) orders antiferromagnetically below T{sub N}=516 K. Neutron powder diffraction at various temperatures 1.5–309 K shows the existence of two distinct magnetic ordering ranges described by the commensurate q{sub 1}=(0, 0, 1/2) and the incommensurate q{sub 2}=(0, 0, q{sub z}) vectors: (i) the HT (high temperature) T{sub t}≈100 KT>1.5 K range has an easy double-cone incommensurately modulated structure described by two vectors (q{sub 1}, q{sub 2}). At 1.5 K q{sub 2}=(0, 0, 0.405(1)), the spiral angle is Φ=145.8° the cone half angle is α≈8° and the ordered moment value μ{sub Mn}=2.12(2) μ{sub B} is the same as for the isomorphic RMn{sub 6}Ge{sub 6} (R=heavy rare earth) compounds. The 1.5 K q{sub 2} satellites are very weak as the in-plane moment component measures only 0.31 μ{sub B}. - Highlights: • T-magnetic phase diagram of antiferromagnetic (afmg.) ScMn{sub 6}Ge{sub 6} compound (T{sub N}=516 K). • 1.5–309 K neutron patterns detected two propagation vectors: q{sub 1}=(0, 0, 1/2) and INC q{sub 2}=(0, 0, q{sub z}). • The HT T{sub t}≈100–309 K range with q{sub 1} has a+− −+Mn moment stacking ||c at z∼1/4, 3/4, 5/4, and 7/4. • The LT range T{sub t}−1.5 K has an easy double cone INC structure requiring both vectors. • At 1.5 K, q{sub 2}=(0, 0, 0.405(1)), the cone half angle 8° and μ{sub Mn}=2.12(2) μ{sub B}.

  10. Hemoglobin redux: combining neutron and X-ray diffraction with mass spectrometry to analyse the quaternary state of oxidized hemoglobins

    Energy Technology Data Exchange (ETDEWEB)

    Mueser, Timothy C., E-mail: timothy.mueser@utoledo.edu; Griffith, Wendell P. [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Kovalevsky, Andrey Y. [Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Guo, Jingshu; Seaver, Sean [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Langan, Paul [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hanson, B. Leif [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States)

    2010-11-01

    X-ray and neutron diffraction studies of cyanomethemoglobin are being used to evaluate the structural waters within the dimer–dimer interface involved in quaternary-state transitions. Improvements in neutron diffraction instrumentation are affording the opportunity to re-examine the structures of vertebrate hemoglobins and to interrogate proton and solvent position changes between the different quaternary states of the protein. For hemoglobins of unknown primary sequence, structural studies of cyanomethemoglobin (CNmetHb) are being used to help to resolve sequence ambiguity in the mass spectra. These studies have also provided additional structural evidence for the involvement of oxidized hemoglobin in the process of erythrocyte senescence. X-ray crystal studies of Tibetan snow leopard CNmetHb have shown that this protein crystallizes in the B state, a structure with a more open dyad, which possibly has relevance to RBC band 3 protein binding and erythrocyte senescence. R-state equine CNmetHb crystal studies elaborate the solvent differences in the switch and hinge region compared with a human deoxyhemoglobin T-state neutron structure. Lastly, comparison of histidine protonation between the T and R state should enumerate the Bohr-effect protons.

  11. Charge structure and cation distribution on Fe-Ga chalcogenide spinel by neutron diffraction and Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sam Jin; Son, Bae Soon; Shim, In Bo; Kim, Chul Sung [Kookmin University, Seoul (Korea, Republic of); Hong, Kun Pyo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2005-07-01

    FeGa{sub x}Cr{sub 2-x}S{sub 4} (x=0.1 and 0.3) have been studied with x-ray, neutron difraction, and Moessbauer spectroscopy. Rietveld refinement of x-ray, neutron diffraction, and Moessbauer spectroscopy lead to the conclusion that the samples are in inverse spinel type, where the majority of Ga ions are present at tetrahedral site (A). The neutron diffractions on FeGa{sub x}Cr{sub 2-x}S{sub 4} (x=0.1) above 10 K show long range interaction behaviors and reveal an antiferromagnetic ordering, with the magnetic moment of Fe{sup 2+}(- 3.45 {mu}{sub B}) aligned antiparallel to Cr{sup 3+} (+2.89 {mu}{sub B}) at 10 K. Fe ions migrate from the tetrahedral (A) site to the octahedral (B) site with increase of Ga substitutions. The electric quadrupole splittings of the A and B sites in Moessbauer spectra give a direct evidence that Ga ion stimulate asymmetric charge distribution of Fe ions in the A site.

  12. Cu-Zn disorder in Cu2ZnGeSe4: A complementary neutron diffraction and Raman spectroscopy study

    Science.gov (United States)

    Gurieva, G.; Többens, D. M.; Valakh, M. Ya.; Schorr, S.

    2016-12-01

    The crystal structure of the quaternary compound semiconductor Cu2ZnGeSe4 (CZGSe) was investigated by the complementary use of neutron diffraction, and Raman spectroscopy. The powder sample, which resulting from wavelength dispersive X-ray spectroscopy (WDX) turned out to be single phase Cu-rich CZGSe, was synthesized by solid state reaction of the pure elements in an evacuated silica tube at 700 °C. Raman spectroscopy confirmed the homogeneity and phase purity of the sample, in addition, the kesterite type structure was suggested. Rietveld analysis of the neutron diffraction data confirmed that the compound crystallizes in the tetragonal kesterite type structure. The refined site occupancy factors were used to determine the average neutron scattering lengths of the cation sites, giving insights into cation distribution and finally point defect types. Thus it has been shown, that additional to the CuZn-ZnCu anti-site defects in the lattice planes at z=¼ and ¾ (Cu-Zn disorder) also the off-stoichiometry type related point defects like Cui and CuZn occur in Cu-rich CZGSe.

  13. Application of an approximate vectorial diffraction model to analysing diffractive micro-optical elements

    Institute of Scientific and Technical Information of China (English)

    Niu Chun-Hui; Li Zhi-Yuan; Ye Jia-Sheng; Gu Ben-Yuan

    2005-01-01

    Scalar diffraction theory, although simple and efficient, is too rough for analysing diffractive micro-optical elements.Rigorous vectorial diffraction theory requires extensive numerical efforts, and is not a convenient design tool. In this paper we employ a simple approximate vectorial diffraction model which combines the principle of the scalar diffraction theory with an approximate local field model to analyse the diffraction of optical waves by some typical two-dimensional diffractive micro-optical elements. The TE and TM polarization modes are both considered. We have found that the approximate vectorial diffraction model can agree much better with the rigorous electromagnetic simulation results than the scalar diffraction theory for these micro-optical elements.

  14. Single-crystal and powder neutron diffraction study of the Fe{sub X}Mn{sub 1−X}S solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Abramova, Galina, E-mail: agm@iph.krasn.ru [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Schefer, Juerg; Aliouane, Nadir [Paul Scherrer Institute, Laboratory for Neutron Scattering (LNS), CH-5232 Villigen PSI (Switzerland); Boehm, Martin [Institut Max von Laue – Paul Langevin, Grenoble Cedex 9 (France); Petrakovskiy, German; Vorotynov, Alexandr [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Gorev, Mikhail [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Institute of Engineering Physics and Radio Electronics, Siberian Federal University, pr. Svobodny 79, Krasnoyarsk 660041 (Russian Federation); Bovina, Asya [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Sokolov, Vladimir [Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)

    2015-05-25

    Highlights: • Fe{sub X}Mn{sub 1−X}S (0 < x < 0.3) with the rock salt structure are synthesized. • Magnetic and structural properties are investigated by the neutron diffraction. • Neel temperature shift from 150 (x = 0) to 200 K (x = 0.29) are found. • The changing of the nuclear and magnetic lattice symmetry was found for Fe{sub X}Mn{sub 1−X}S (0.25 < x < 0.29). - Abstract: The α-MnS-based Fe{sub X}Mn{sub 1−X}S (0 < x < 0.3) solid solutions are synthesized and shown to be new Mott materials with the rock salt structure. Neutron diffraction data show that the chemical-pressure-induced Neel temperature shift from 150 (x = 0) to 200 K (x = 0.29) observed in these materials is accompanied by a decrease in the NaCl-type cubic lattice parameters. It is established that at the symmetry transformation in the compositions with x = 0.25 and 0.29 the structural transition occurs, which is followed by the magnetic transition. These features make the Fe{sub X}Mn{sub 1−X}S solid solutions interesting for both fundamental study of the interrelation between the magnetic, electrical, and structural properties in MnO-type strongly correlated electron systems and application.

  15. Hydrogen adsorption in a highly stable porous rare-earth metal-organic framework: sorption properties and neutron diffraction studies.

    Science.gov (United States)

    Luo, Junhua; Xu, Hongwu; Liu, Yun; Zhao, Yusheng; Daemen, Luke L; Brown, Craig; Timofeeva, Tatiana V; Ma, Shengqian; Zhou, Hong-Cai

    2008-07-30

    A highly stable porous lanthanide metal-organic framework, Y(BTC)(H2O).4.3H2O (BTC = 1,3,5-benzenetricarboxylate), with pore size of 5.8 A has been constructed and investigated for hydrogen storage. Gas sorption measurements show that this porous MOF exhibits highly selective sorption behaviors of hydrogen over nitrogen gas molecules and can take up hydrogen of about 2.1 wt % at 77 K and 10 bar. Difference Fourier analysis of neutron powder diffraction data revealed four distinct D2 sites that are progressively filled within the nanoporous framework. Interestingly, the strongest adsorption sites identified are associated with the aromatic organic linkers rather than the open metal sites, as occurred in previously reported MOFs. Our results provide for the first time direct structural evidence demonstrating that optimal pore size (around 6 A, twice the kinetic diameter of hydrogen) strengthens the interactions between H2 molecules and pore walls and increases the heat of adsorption, which thus allows for enhancing hydrogen adsorption from the interaction between hydrogen molecules with the pore walls rather than with the normally stronger adsorption sites (the open metal sites) within the framework. At high concentration H2 loadings (5.5 H2 molecules (3.7 wt %) per Y(BTC) formula), H2 molecules form highly symmetric novel nanoclusters with relatively short H2-H2 distances compared to solid H2. These observations are important and hold the key to optimizing this new class of rare metal-organic framework (RMOF) materials for practical hydrogen storage applications.

  16. Structure of molten CaSiO3: neutron diffraction isotope substitution with aerodynamic levitation and molecular dynamics study.

    Science.gov (United States)

    Skinner, L B; Benmore, C J; Weber, J K R; Tumber, S; Lazareva, L; Neuefeind, J; Santodonato, L; Du, J; Parise, J B

    2012-11-15

    We have performed neutron diffraction isotopic substitution experiments on aerodynamically levitated droplets of CaSiO(3), to directly extract intermediate and local structural information on the Ca environment. The results show a substantial broadening of the first Ca-O peak in the pair distribution function of the melt compared to the glass, which comprises primarily of 6- and 7-fold coordinated Ca-polyhedra. The broadening can be explained by a redistribution of Ca-O bond lengths, especially toward longer distances in the liquid. The first order neutron difference function provides a test of recent molecular dynamics simulations and supports the MD model which contains short chains or channels of edge shared Ca-octahedra in the liquid state. It is suggested that the polymerization of Ca-polyhedra is responsible for the fragile viscosity behavior of the melt and the glass forming ability in CaSiO(3).

  17. The structure of molten CaSiO3: A neutron diffraction isotope substitution and aerodynamic levitation study.

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Lawrie [State University of New York, Stony Brook; Benmore, Chris J [Argonne National Laboratory (ANL); Weber, Richard [Argonne National Laboratory (ANL); Santodonato, Louis J [ORNL; Tumber, Sonia [Materials Development, Inc., Evanston, IL; Neuefeind, Joerg C [ORNL; Lazareva, Lena [State University of New York, Stony Brook; Du, Jincheng [University of North Texas; Parise, John B [Stony Brook University (SUNY)

    2012-01-01

    We have performed neutron diffraction isotopic substitution experiments on aerodynamically levitated droplets of CaSiO3, to directly extract intermediate and local structural information on the Ca environment. The results show a substantial broadening of the Ca-O peak in the pair distribution function of the melt compared to the glass, which comprises primarily of 6- and 7-fold coordinated Ca-polyhedra. The broadening can be explained by a re-distribution of Ca-O bond lengths, especially towards longer distances in the liquid. The first order neutron difference function provides a rigorous test of recent molecular dynamics simulations and supports the model of the presence of short chains or channels of edge shared Ca-octahedra in the liquid state. It is suggested that the polymerization of Ca-polyhedra is responsible for the fragile viscosity behavior of the melt and the glass forming ability in CaSiO3.

  18. Application of Diamond Nanoparticles in Low-Energy Neutron Physics

    Directory of Open Access Journals (Sweden)

    Alexander Strelkov

    2010-03-01

    Full Text Available Diamond, with its exceptionally high optical nuclear potential and low absorption cross-section, is a unique material for a series of applications in VCN (very cold neutron physics and techniques. In particular, powder of diamond nanoparticles provides the best reflector for neutrons in the complete VCN energy range. It allowed also the first observation of quasi-specular reflection of cold neutrons (CN from disordered medium. Effective critical velocity for such a quasi-specular reflection is higher than that for the best super-mirror. Nano-diamonds survive in high radiation fluxes; therefore they could be used, under certain conditions, in the vicinity of intense neutron sources.

  19. Neutron imaging and applications a reference for the imaging community

    CERN Document Server

    McGreevy, Robert L; Bilheux, Hassina Z

    2009-01-01

    Offers an introduction to the basics of neutron beam production in addition to the wide scope of techniques that enhance imaging application capabilities. This title features a section that describes imaging single grains in polycrystalline materials, neutron imaging of geological materials and other materials science and engineering areas.

  20. Compound Refractive Lenses for Thermal Neutron Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gary, Charles K.

    2013-11-12

    This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 μm which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

  1. Determination of the hexagonal network parameters of the quartz {beta} using neutron multiple diffraction; Determinacao dos parametros da rede hexagonal do quartzo {beta} utilizando difracao multipla de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Campos, L.C.; Parente, C.B.R.; Mazzocchi, V.L. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: lccampos@curiango.ipen.br; Helene, O. [Universidade de Sao Paulo (USP), SP (Brazil)], e-mail: otaviano@if.usp.br

    2000-07-01

    In this work, neutron multiple diffraction is employed for the determination of the parameters a and c of the {beta}-quartz hexagonal cell. This crystalline phase of silica (SiO{sub 2}) occurs in temperatures between ca. 846 and 1143 K. A {beta}-quartz neutron multiple diffraction pattern has been used in the determinations. This pattern was obtained with a natural quartz single crystal heated to 1003 K. During the indexing of the pattern it was verified that most of the pairs of secondary reflections, which are responsible for the formation of peaks, could be classified as 'good for the determination of a' or 'good for the determination of c'. With this classification, it became possible to employ an iterative method for the determination of both parameters. After 8 cycles of iteration the values found for the parameters were a = 4.9964 +- 0.0018 and c = 5.46268 +- 0.00052 A. (author)

  2. Neutron diffraction studies of the magnetic structure of Ho{sub 3}Pd{sub 4}Ge{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzynska, E.; Penc, B.; Hernandez-Velasco, J.; Szytula, A.; Zygmunt, A

    2003-02-17

    Ho{sub 3}Pd{sub 4}Ge{sub 4} crystallizes in the orthorhombic Gd{sub 6}Cu{sub 8}Ce{sub 8}-type of structure (space group Immm) in which the Ho atoms occupy two nonequivalent crystallographic positions: 2a and 4j. Neutron diffraction measurements indicate that the Ho moments in the 4j site below 6.7 K form a collinear antiferromagnetic structure with the magnetic moments parallel to the a axis, whereas the Ho moments in the 2a site below 5 K form a sine-wave modulated structure with the magnetic moments parallel to the c axis.

  3. Neutron powder diffraction studies of LiIO 3 and (HIO 3, 2LiIO 3)

    Science.gov (United States)

    Bouillot, J.; Coquet, E.; Pannetier, J.; Crettez, J.-M.

    1986-02-01

    A study of the kinetics of transition of powdered samples of LiIO 3 has been performed in order to determine the domain of stability of the γ-phase and to refine its structure. For a better undertanding of the transition mechanism which may involve the presence of proton impurities, the decomposition of (HIO 3, 2LiIO 3), while increasing the temperature, has been recorded continuously by means of neutron powder diffraction and the different features appearing in the observed patterns have been analyzed. A tentative interpretation is given.

  4. In situ x-ray and neutron powder diffraction study of LaNi5-xSnx-H systems

    Science.gov (United States)

    Bowman, Robert C., Jr.; Nakamara, Yumiko; Akiba, Etsuo

    2004-01-01

    This paper will present results of in situ XRD measurements of LaNi4.75Sn0.25 .during the initial absorption-desorption cycle, These measurements were performed under a similar condition to that for LaNi4.75Al0.25 previously reported [1]. The data were analyzed by the Rietveld method. Lattice parameter change and strain formation accompanying hydride phase formation and decomposition will be discussed. In addition, results of in situ neutron diffraction of LaNi4.78Sn0.22, focusing on hydrogen occupation in the hydride phase, will be presented.

  5. Effect of non-isothermal deformation of austenite on ferrite transformation behavior studied by in-situ neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zengmin, E-mail: shzm@ctgu.edu.cn [College of Materials and Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Tomota, Yo [Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Harjo, Stefanus; Su, Yuhua [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan); Chi, Bo; Pu, Jian [School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Jian, Li, E-mail: lijian@hust.edu.cn [School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-04-17

    The microstructure evolution and phase transformation of high strength 22SiMn2TiB steel during non-isothermal deformation were investigated by using in situ time-of-flight (TOF) neutron diffraction technique. The results indicate that the deformation of austenite promotes pearlite and ferrite transformation while suppresses bainite transformation. Deformation texture forms in austenite and then it influences the evolution of transformation texture. Deformation of austenite brings the changes in lattice parameters of austenite caused by carbon partitioning and elastic strains during the transformation. Volume fraction of the retained austenite decreases with a decreased carbon content as deformation amount increases.

  6. Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings

    Science.gov (United States)

    Stegemann, Robert; Cabeza, Sandra; Lyamkin, Viktor; Bruno, Giovanni; Pittner, Andreas; Wimpory, Robert; Boin, Mirko; Kreutzbruck, Marc

    2017-03-01

    The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction (ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth.

  7. Neutron diffraction analyses of U-(6-10 wt.%)Mo alloy powders fabricated by centrifugal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Man [Advanced Fuel Technology Development Division, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong, Daejeon 305-353 (Korea, Republic of); Ryu, Ho Jin, E-mail: hjryu@kaeri.re.k [Advanced Fuel Technology Development Division, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong, Daejeon 305-353 (Korea, Republic of); Kim, Ki Hwan; Lee, Don Bae; Lee, Yoon Sang [Advanced Fuel Technology Development Division, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong, Daejeon 305-353 (Korea, Republic of); Lee, Jeong Soo; Seong, Baek Seok [Neutron Science Division, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong, Daejeon 305-353 (Korea, Republic of); Kim, Chang Kyu [Advanced Fuel Technology Development Division, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong, Daejeon 305-353 (Korea, Republic of); Cornen, Marilyne [INSA de Rennes, UMR CNRS 6226 Sciences Chimiques de Rennes/Chimie-Metallurgie, 20 Avenue des Buttes de Coesmes, 35043 Rennes Cedex (France)

    2010-02-15

    Lattice parameters of U-(6-10 wt.%)Mo alloy powders fabricated by a centrifugal atomization technique were measured by neutron diffraction analyses. A micro-segregation of Mo at cell boundaries was observed in the centrifugally atomized U-Mo alloy powders with varying Mo content. Lattice parameters of gamma phases decrease linearly with the increasing Mo content. By separating the overlapped diffraction peaks from cell boundaries and cell interior, lattice parameters and Mo contents of each region were calculated. The Mo content at cell boundaries is about 2-5 at.% lower than that in the cell interior and the lattice parameters for the cell boundaries are higher than those for the cell interior of the atomized U-Mo powder.

  8. Neutron diffraction analyses of U-(6-10 wt.%)Mo alloy powders fabricated by centrifugal atomization

    Science.gov (United States)

    Park, Jong Man; Ryu, Ho Jin; Kim, Ki Hwan; Lee, Don Bae; Lee, Yoon Sang; Lee, Jeong Soo; Seong, Baek Seok; Kim, Chang Kyu; Cornen, Marilyne

    2010-02-01

    Lattice parameters of U-(6-10 wt.%)Mo alloy powders fabricated by a centrifugal atomization technique were measured by neutron diffraction analyses. A micro-segregation of Mo at cell boundaries was observed in the centrifugally atomized U-Mo alloy powders with varying Mo content. Lattice parameters of gamma phases decrease linearly with the increasing Mo content. By separating the overlapped diffraction peaks from cell boundaries and cell interior, lattice parameters and Mo contents of each region were calculated. The Mo content at cell boundaries is about 2-5 at.% lower than that in the cell interior and the lattice parameters for the cell boundaries are higher than those for the cell interior of the atomized U-Mo powder.

  9. Local order and orientational correlations in liquid and crystalline phases of carbon tetrabromide from neutron powder diffraction measurements

    CERN Document Server

    Temleitner, László

    2010-01-01

    The liquid, plastic crystalline and ordered crystalline phases of CBr$_4$ were studied using neutron powder diffraction. The measured total scattering differential cross-sections were modelled by Reverse Monte Carlo simulation techniques (RMC++ and RMCPOW). Following successful simulations, the single crystal diffraction pattern of the plastic phase, as well as partial radial distribution functions and orientational correlations for all the three phases have been calculated from the atomic coordinates ('particle configurations'). The single crystal pattern, calculated from a configuration that had been obtained from modelling the powder pattern, shows identical behavior to the recent single crystal data of Folmer et al. (Phys. Rev. {\\bf B77}, 144205 (2008)). The BrBr partial radial distribution functions of the liquid and plastic crystalline phases are almost the same, while CC correlations clearly display long range ordering in the latter phase. Orientational correlations also suggest strong similarities bet...

  10. Neutron powder diffraction study on Mg sup 1 sup 1 B sub 2 synthesized by different procedures

    CERN Document Server

    Oikawa, K; Arai, M; Mochiku, T; Takeya, H; Furuyama, M; Kamisawa, S; Kadowaki, K

    2002-01-01

    The crystal structure of a new superconducting material, MgB sub 2 , was studied by high-resolution neutron powder diffraction as a function of temperature from 8K to 305K. Two samples of Mg sup 1 sup 1 B sub 2 were measured; one was synthesized for 2d at 1050degC, and the other one was done for 1d at 1100degC. All of the diffraction data were precisely refined by the Rietveld method, and we confirmed that there was no clear anomaly on the temperature dependence of the lattice constants around T sub c for both samples. The difference in sample synthesis procedures affects the profile shapes of the 001 reflections, whereas the hh0 lines are almost the same.

  11. Neutron scattering applications in hydrocarbon materials

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Min Y.; Peiffer, Dennis G. [ExxonMobil Research and Engineering Company, Annandale, NJ (United States); Zhang, Yimin; Rafailovich, Miriam [Dept. of Materials Sci. and Eng., State University of New York, NY (United States)

    2001-03-01

    Neutron scattering methods are a powerful probe to complex fluids, soft matters as well as solid materials of nano- and micro-structures and their related dynamic properties. They complement other microstructural probing tools, such as microscopes, x-ray and light scattering techniques. Because neutron does not carry charges, it interacts only with nuclei of the matter, therefore not only can it penetrate a longer length into matters, it can also see' many features other methods can't due to their lack of proper contrast or heavy absorption. One of the largest contrasts in neutron methods is from hydrogen/deuterium (H/D) difference. Therefore, hydrocarbons can be easily studied by neutrons when H/D isotope substitution is applied. Here at National Institute of Standards and Technology's Center for Neutron Research (NCNR) in Gaithersburg, Maryland, one of the USA's premier neutron scattering facilities, we have been using neutron scattering techniques to study microstructures of asphaltenes, waxes, gas hydrates, porous media, surfactant solutions, engine oils, polymers, nanocomposites, fuel cell element and other hydrocarbon materials. With the completion of a new Neutron Spin Echo instrument, we can also look at the dynamics of the above mentioned systems. (author)

  12. Application Research of Developed Drummed Nuclear Waste Neutron Counting System

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The application researches such as variety of factors affecting the measurement, calibrating etc. are need before the drummed nuclear waste neutron counting system (WNC) can be really put into use after installed at the site.

  13. 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.

  14. Quantitative analysis of hydrogen sites and occupancy in deep mantle hydrous wadsleyite using single crystal neutron diffraction

    Science.gov (United States)

    Purevjav, Narangoo; Okuchi, Takuo; Tomioka, Naotaka; Wang, Xiaoping; Hoffmann, Christina

    2016-01-01

    Evidence from seismological and mineralogical studies increasingly indicates that water from the oceans has been transported to the deep earth to form water-bearing dense mantle minerals. Wadsleyite [(Mg, Fe2+)2SiO4] has been identified as one of the most important host minerals incorporating this type of water, which is capable of storing the entire mass of the oceans as a hidden reservoir. To understand the effects of such water on the physical properties and chemical evolution of Earth’s interior, it is essential to determine where in the crystal structure the hydration occurs and which chemical bonds are altered and weakened after hydration. Here, we conduct a neutron time-of-flight single-crystal Laue diffraction study on hydrous wadsleyite. Single crystals were grown under pressure to a size suitable for the experiment and with physical qualities representative of wet, deep mantle conditions. The results of this neutron single crystal diffraction study unambiguously demonstrate the method of hydrogen incorporation into the wadsleyite, which is qualitatively different from that of its denser polymorph, ringwoodite, in the wet mantle. The difference is a vital clue towards understanding why these dense mantle minerals show distinctly different softening behaviours after hydration. PMID:27725749

  15. Quantitative analysis of hydrogen sites and occupancy in deep mantle hydrous wadsleyite using single crystal neutron diffraction

    Science.gov (United States)

    Purevjav, Narangoo; Okuchi, Takuo; Tomioka, Naotaka; Wang, Xiaoping; Hoffmann, Christina

    2016-10-01

    Evidence from seismological and mineralogical studies increasingly indicates that water from the oceans has been transported to the deep earth to form water-bearing dense mantle minerals. Wadsleyite [(Mg, Fe2+)2SiO4] has been identified as one of the most important host minerals incorporating this type of water, which is capable of storing the entire mass of the oceans as a hidden reservoir. To understand the effects of such water on the physical properties and chemical evolution of Earth’s interior, it is essential to determine where in the crystal structure the hydration occurs and which chemical bonds are altered and weakened after hydration. Here, we conduct a neutron time-of-flight single-crystal Laue diffraction study on hydrous wadsleyite. Single crystals were grown under pressure to a size suitable for the experiment and with physical qualities representative of wet, deep mantle conditions. The results of this neutron single crystal diffraction study unambiguously demonstrate the method of hydrogen incorporation into the wadsleyite, which is qualitatively different from that of its denser polymorph, ringwoodite, in the wet mantle. The difference is a vital clue towards understanding why these dense mantle minerals show distinctly different softening behaviours after hydration.

  16. Lithium plating in lithium-ion batteries at sub-ambient temperatures investigated by in situ neutron diffraction

    Science.gov (United States)

    Zinth, Veronika; von Lüders, Christian; Hofmann, Michael; Hattendorff, Johannes; Buchberger, Irmgard; Erhard, Simon; Rebelo-Kornmeier, Joana; Jossen, Andreas; Gilles, Ralph

    2014-12-01

    Lithium plating in commercial LiNi1/3Mn1/3Co1/3O2/graphite cells at sub-ambient temperatures is studied by neutron diffraction at Stress-Spec, MLZ. Li plating uses part of the active lithium in the cell and competes with the intercalation of lithium into graphite. As a result, the degree of graphite lithiation during and after charge is lower. Comparison of graphite lithiation after a C/5 charging cycle fast enough to expect a considerable amount of Li plating with a much slower C/30 reference cycle reveals a lower degree of graphite lithiation in the first case; neutron diffraction shows less LiC6 and more LiC12 is present. If the cell is subjected to a 20 h rest period after charge, a gradual transformation of remaining LiC12 to LiC6 can be observed, indicating Li diffusion into the graphite. During the rest period after the C/5 charging cycle, the degree of graphite lithiation can be estimated to increase by 17%, indicating at least 17% of the active lithium is plated. Data collected during discharge immediately after C/5 charging give further evidence of the presence and amount of metallic lithium: in this case 19% of discharge capacity originates from the oxidation of metallic lithium. Also, lithium oxidation can be directly related to the high voltage plateau observed during discharge in case of lithium plating.

  17. Neutron diffraction evidence for kinetic arrest of first order magneto-structural phase transitions in some functional magnetic materials.

    Science.gov (United States)

    Siruguri, V; Babu, P D; Kaushik, S D; Biswas, Aniruddha; Sarkar, S K; Krishnan, Madangopal; Chaddah, P

    2013-12-11

    Neutron diffraction measurements, performed in the presence of an external magnetic field, have been used to show structural evidence for the kinetic arrest of the first order phase transition from (i) the high temperature austenite phase to the low temperature martensite phase in the magnetic shape memory alloy Ni37Co11Mn42.5Sn9.5, (ii) the higher temperature ferromagnetic phase to the lower temperature antiferromagnetic phase in the half-doped charge ordered compound La0.5Ca0.5MnO3 and (iii) the formation of glass-like arrested states in both compounds. The cooling and heating under unequal fields protocol has been used to establish phase coexistence of metastable and equilibrium states, and also to demonstrate the devitrification of the arrested metastable states in the neutron diffraction patterns. We also explore the field–temperature dependent kinetic arrest line TK(H), through the transformation of the arrested phase to the equilibrium phase. This transformation has been observed isothermally in reducing H, as also on warming in constant H. TK is seen to increase as H increases in both cases, consistent with the low-T equilibrium phase having lower magnetization.

  18. In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Jean-Marie Drezet

    2014-02-01

    Full Text Available The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e., strong enough, to avoid hot tear formation.

  19. Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Sarah [University of Alabama, Birmingham; Montgomery, Jeffrey M [University of Alabama, Birmingham; Tsoi, Georgiy [University of Alabama, Birmingham; Vohra, Yogesh [University of Alabama, Birmingham; Chesnut, Gary Neal [University of Alabama, Birmingham; Weir, S. T. [Lawrence Livermore National Laboratory (LLNL); Tulk, Christopher A [ORNL; Moreira Dos Santos, Antonio F [ORNL

    2013-01-01

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare-earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic (FM) order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the FM Curie temperature. The temperature of this FM transition decreases at a rate of-16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of FM order is suppressed. The neutron diffraction measurements as a function of pressure at temperatures ranging from 90 to 290 K confirm that the change of slope in the resistance is associated with the FM ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. A disappearance of FM ordering was observed as the pressure is increased above 3.6 GPa and is correlated with the phase transition from the ambient hexagonal close packed structure to an -Sm-type structure at high pressures.

  20. Mechanochemical synthesis in the Li-Mg-N-D system under deuterium gas: a neutron diffraction study.

    Science.gov (United States)

    Li, Z; Zhang, J; Latroche, M; Wang, S; Jiang, L; Du, J; Cuevas, F

    2016-09-14

    The Mg(NH2)2/2LiH mixture is considered as one of the most valuable reversible hydrogen storage systems for feeding PEM fuel cells. In this paper, we investigate the mechanochemical synthesis in the Li-Mg-N-H system under deuterium gas, using Li3N and Mg as reactants, and the structural and sorption properties of the intermediate and final products mainly by means of neutron powder diffraction. Mechanochemistry leads to the end formation of amorphous Mg(ND2)2, which crystallizes upon heating above 425 K. During synthesis, a novel cation-mixed nitride/imide phase of simplified composition Li3MgN2D has been unveiled as the intermediate phase. It crystallizes in the cubic disordered anti-fluorite type structure (S.G. Fm3[combining macron]m) with a lattice parameter of 4.996 Å at room temperature. Deuterium absorption in this compound occurs through an original solid solution type mechanism ending with the imide compound β-Li2MgN2D2. The conjoint use of mechanochemistry under deuterium gas and in situ neutron diffraction techniques offers new avenues for better characterization of the efficient hydrogen storage materials. In particular, this work highlights the unexpected role of intermediate nitride/imide phases in the Li-Mg-N-H system.

  1. CO2 Adsorption to Sub-Single Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot [ORNL; Ilton, Eugene [Pacific Northwest National Laboratory (PNNL); Wallacher, Dirk [Helmholtz-Zentrum Berlin; Hauss, Thomas [Helmholtz-Zentrum Berlin; Schaef, Herbert [Pacific Northwest National Laboratory (PNNL); Qafoku, Odeta [Pacific Northwest National Laboratory (PNNL); Rosso, Kevin M. [Pacific Northwest National Laboratory (PNNL); Felmy, Andrew [Pacific Northwest National Laboratory (PNNL); Krukowski, Elizabeth G [ORNL; Stack, Andrew G [ORNL; Bodnar, Robert J [ORNL

    2013-01-01

    Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable by CO2. Swelling clays, which are important components of caprocks, may react with CO2 under volume change, potentially impacting the seal quality. The interactions of scCO2 with Na saturated montmorillonite clay containing a sub-single layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of 0.15 g/cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 . The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay-CO2 phase. At low pressure increasing CO2 adsorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak or no temperature dependence. Supercritical fluids, sorption phenomena, carbon dioxide, carbon sequestration, caprock integrity

  2. CO2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk; Hauβ, Thomas; Schaef, Herbert T.; Qafoku, Odeta; Rosso, Kevin M.; Felmy, Andrew R.; Krukowski, Elizabeth G.; Stack, Andrew G.; Grimm, Nico; Bodnar, Robert J.

    2013-01-02

    Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable to CO2. Swelling clays, which are important components of caprocks, may interact with CO2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay-CO2 phase. Finally, at the excess sorption maximum, increasing CO2 sorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak temperature dependence.

  3. Enhanced crystal fabric analysis of a lava flow sample by neutron texture diffraction: A case study from the Castello d'Ischia dome

    Science.gov (United States)

    Walter, Jens M.; Iezzi, Gianluca; Albertini, Gianni; Gunter, Mickey E.; Piochi, Monica; Ventura, Guido; Jansen, Ekkehard; Fiori, Fabrizio

    2013-01-01

    The crystal fabric of a lava has been analyzed for the first time by neutron texture diffraction. In this study we quantitatively investigate the crystallographic preferred orientation of feldspars in the Castello d'Ischia (Ischia Island, Italy) trachytic exogenous dome. The crystallographic preferred orientation was measured with the monochromatic neutron texture diffractometer SV7 at the Forschungszentrum Jülich in Germany and a Rietveld refinement was applied to the sum diffraction pattern. The complementary thin section analysis showed that the three-dimensional crystal shape and the corresponding shape preferred orientation are in agreement with the quantitative orientation distributions of the neutron texture data. The (0k0) crystallographic planes of the feldspars are roughly parallel to the local flow bands, whereas the other corresponding pole figures show that a pivotal rotation of the anorthoclase and sanidine crystals was active during the emplacement of this lava dome. In combination with scanning electron microscopy investigations, electron probe microanalysis, XRF, and X-ray diffraction, the Rietveld refinement of the neutron diffraction data indicates a slow cooling dynamic on the order of several months during their crystallization under subaerial conditions. Results attained here demonstrate that neutron texture diffraction is a powerful tool that can be applied to lava flows.

  4. The sciences and applications of the Electron LINAC-driven neutron source in Argentina

    Science.gov (United States)

    Granada, J. R.; Mayer, R. E.; Dawidowski, J.; Santisteban, J. R.; Cantargi, F.; Blostein, J. J.; Rodríguez Palomino, L. A.; Tartaglione, A.

    2016-06-01

    The Neutron Physics group at Centro Atómico Bariloche (CNEA, Argentina) has evolved for more than forty five years around a small 25MeV linear electron accelerator. It constitutes our compact accelerator-driven neutron source (CANS), which is dedicated to the use and development of neutronic methods to tackle problems of basic sciences and technological applications. Its historical first commitment has been the determination of the total cross sections of materials as a function of neutron energy by means of transmission experiments for thermal and sub-thermal neutrons. This also allowed testing theoretical models for the generation of scattering kernels and cross sections. Through the years, our interests moved from classic pulsed neutron diffraction, which included the development of high-precision methods for the determination of very low hydrogen content in metals, towards deep inelastic neutron scattering (DINS), a powerful tool for the determination of atomic momentum distribution in condensed matter. More recently non-intrusive techniques aimed at the scanning of large cargo containers have started to be developed with our CANS, testing the capacity and limitations to detect special nuclear material and dangerous substances. Also, the ever-present "bremsstrahlung" radiation has been recognized and tested as a useful complement to instrumental neutron activation, as it permits to detect other nuclear species through high-energy photon activation. The facility is also used for graduate and undergraduate students' experimental work within the frame of Instituto Balseiro Physics and Nuclear Engineering courses of study, and also MSc and PhD theses work.

  5. Neutron Scattering in Biology Techniques and Applications

    CERN Document Server

    Fitter, Jörg; Katsaras, John

    2006-01-01

    The advent of new neutron facilities and the improvement of existing sources and instruments world wide supply the biological community with many new opportunities in the areas of structural biology and biological physics. The present volume offers a clear description of the various neutron-scattering techniques currently being used to answer biologically relevant questions. Their utility is illustrated through examples by some of the leading researchers in the field of neutron scattering. This volume will be a reference for researchers and a step-by-step guide for young scientists entering the field and the advanced graduate student.

  6. Magnetic octupole order in Ce0.7La0.3B6: A polarized neutron diffraction study

    Science.gov (United States)

    Kuwahara, K.; Iwasa, K.; Kohgi, M.; Aso, N.; Sera, M.; Iga, F.; Matsuura, M.; Hirota, K.

    2009-09-01

    Recently, in phase IV of CexLa1-xB6, weak but distinct superlattice reflections from the order parameter of phase IV have been detected by our unpolarized neutron scattering experiment [K. Kuwahara, K. Iwasa, M. Kohgi, N. Aso, M. Sera, F. Iga, J. Phys. Soc. Japan 76 (2007) 093702]. The scattering vector dependence of the intensity of superlattice reflections is quite unusual; the intensity is stronger for high scattering vectors. This result strongly indicates that the order parameter of phase IV is the magnetic octupole. However, the possibility that the observed superlattice reflections are due to lattice distortions could not be completely ruled out only on the basis of the unpolarized neutron scattering experiment. To confirm that the superlattice reflections are magnetic, therefore, we have performed a single crystal polarized neutron diffraction experiment on Ce0.7La0.3B6. The obtained result has clearly shown that the time reversal symmetry is broken by the order parameter of phase IV. This is further evidence for the magnetic octupole order in CexLa1-xB6.

  7. First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments

    Directory of Open Access Journals (Sweden)

    Maxime Deutsch

    2014-05-01

    Full Text Available Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.

  8. Arrangement of ceramide [EOS] in a stratum corneum lipid model matrix: new aspects revealed by neutron diffraction studies.

    Science.gov (United States)

    Kessner, Doreen; Kiselev, Mikhail; Dante, Silvia; Hauss, Thomas; Lersch, Peter; Wartewig, Siegfried; Neubert, Reinhard H H

    2008-07-01

    The lipid matrix in stratum corneum (SC) plays a key role in the barrier function of the mammalian skin. The major lipids are ceramides (CER), cholesterol (CHOL) and free fatty acids (FFA). Especially the unique-structured omega-acylceramide CER[EOS] is regarded to be essential for skin barrier properties by inducing the formation of a long-periodicity phase of 130 angstroms (LPP). In the present study, the arrangement of CER[EOS], either mixed with CER[AP] and CHOL or with CER[AP], CHOL and palmitic acid (PA), inside a SC lipid model membrane has been studied for the first time by neutron diffraction. For a mixed CER[EOS]/CER[AP]/CHOL membrane in a partly dehydrated state, the internal membrane nanostructure, i.e. the neutron scattering length density profile in the direction normal to the surface, was obtained by Fourier synthesis from the experimental diffraction patterns. The membrane repeat distance is equal to that of the formerly used SC lipid model system composed of CER[AP]/CHOL/PA/ChS. By comparing both the neutron scattering length density profiles, a possible arrangement of synthetic long-chain CER[EOS] molecules inside a SC lipid model matrix is suggested. The analysis of the internal membrane nanostructure implies that one CER[EOS] molecule penetrates from one membrane layer into an adjacent layer. A 130 angstroms periodicity phase could not be observed under experimental conditions, either in CER/CHOL mixtures or in CER/CHOL/FFA mixture. CER[EOS] can be arranged inside a phase with a repeat unit of 45.2 angstroms which is predominately formed by short-chain CER[AP] with distinct polarity.

  9. Ferroelastic contribution to the piezoelectric response in lead zirconate titanate by in situ stroboscopic neutron diffraction

    Science.gov (United States)

    Jones, Jacob L.; Hoffman, Mark; Daniels, John E.; Studer, Andrew J.

    2006-11-01

    Ferroelastic domain switching during dynamic actuation is measured in situ for a piezoelectric lead zirconate titanate (PZT) ceramic utilizing a new capability developed on The Australian Strain Scanner (TASS) at ANSTO. Diffraction patterns are obtained as a function of time during a 1 Hz cycle. The change in the 0 0 2 and 2 0 0 diffraction intensities indicates there is ferroelastic domain switching at sub-coercive (weak) fields.

  10. Pair-correlation function in disordered β-brass as studied by neutron diffraction

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.

    1967-01-01

    Critical neutron scattering around a superlattice reflection above Tc yields information on the pair correlation function for occupation of lattice sites. The Ornstein-Zernike correlation function e-k 1 r/r is proved to fit the data excellently, and at 8.9deg K above Tc the inverse correlation ra...

  11. The effect of experimental resolution on crystal reflectivity and secondary extinction in neutron diffraction

    DEFF Research Database (Denmark)

    Dietrich, O.W.; Als-Nielsen, Jens Aage

    1965-01-01

    The reflectivity for neutrons of a plane slab crystal is calculated in the transmission case when the crystal is placed between two Seller collimators. The calculations indicate that the crystal reflectivity, as well as the secondary extinction coefficient, depends signicantly on the angular...... resolution of the collimators. Curves are given for the extinction of the crystal with different crystal and collimator parameters....

  12. Small angle neutron diffraction studies of vortex structures in high temperature superconductors

    DEFF Research Database (Denmark)

    Cubitt, R.; Forgan, E.M.; Wylie, M.T.

    1994-01-01

    We have used neutron scattering to provide direct information about flux structures in the bulk of crystals of the superconductor Bi2Sr2CaCu2O8. Its extremely high effective mass anisotropy, makes the flux lattice susceptable to melting and also to decomposition into 'pancake' vortices, which would...

  13. Development of a prompt gamma activation analysis facility using diffracted polychromatic neutron beam

    CERN Document Server

    Byun, S H; Choi, H D

    2002-01-01

    A prompt gamma activation analysis facility has recently been developed at Hanaro, the 24 MW research reactor in the Korea Atomic Energy Research Institute. Polychromatic thermal neutrons are extracted by setting pyrolytic graphite crystals at a Bragg angle of 45 deg. . The detection system comprises a large single n-type HPGe detector, signal electronics and a fast ADC. Neutron beam characterization was performed both theoretically and experimentally. The neutron flux was measured to be 7.9x10 sup 7 n/cm sup 2 s in a 1x1 cm sup 2 beam area at the sample position with a uniformity of 12%. The corresponding Cd-ratio for gold was found to be 266. The beam quality was compared with other representative thermal neutron prompt gamma activation analysis. The detection efficiency was calibrated up to 11 MeV using a set of radionuclides and the (n,gamma) reactions of N and Cl. Finally, the sensitivities and the detection limits were obtained for several elements.

  14. A Review of Neutron Scattering Applications to Nuclear Materials

    OpenAIRE

    VOGEL, Sven.C

    2013-01-01

    The growing demand for electric energy will require expansion of the amount of nuclear power production in many countries of the world. Research and development in this field will continue to grow to further increase safety and efficiency of nuclear power generation. Neutrons are a unique probe for a wide range of problems related to these efforts, ranging from crystal chemistry of nuclear fuels to engineering diffraction on cladding or structural materials used in nuclear reactors. Increased...

  15. Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, H.S.H.; Stevens, R.C.; Bau, R. (Univ. of Southern California, Los Angeles, CA (United States)); Mosher, H.S. (Stanford Univ., CA (United States)); Koetzle, T.F. (Brookhaven National Lab., Upton, NY (United States))

    1994-12-20

    The absolute configuration of (+)-neopentyl-1-d alcohol, prepared by the reduction of 2,2-dimethylpropanol-1-d by actively fermenting yeast, has been determined to be S by neutron diffraction. The neutron study was carried out on the phthalate half ester of neopentyl-1-d alcohol, crystallized as its strychnine salt. The absolute configuration of the (-)-strychninium cation was first determined by an x-ray anomalous dispersion study of its iodide salt. The chiral skeleton of strychnine then served as a reference from which the absolute configuration of the -O-CHD-C(CH[sub 3])[sub 3] group of neopentyl phthalate was determined. Difference Fourier maps calculated from the neutron data showed unambiguously that the -O-CHD-C(CH[sub 3])[sub 3] groups of both independent molecules in the unit cell had the S configuration. This work proves conclusively that the yeast system reduces aldehydes by delivering hydrogen to the re face of the carbonyl group. Crystallographic details: (-)-strychninium (+)-neopentyl-1-d phthalate, space group P2[sub 1] (monoclinic), a = 18.564(6) [angstrom], b = 7.713(2) [angstrom], c = 23.361(8) [angstrom], [beta] = 94.18(4)[degrees], V = 3336.0(5) [angstrom][sup 3], Z = 2 (T = 100 K). Final agreement factors are R(F) = 0.073 for 2768 reflections collected at room temperature (x-ray analysis) and R(F) = 0.144 for 960 reflections collected at 100 K (neutron analysis). 49 refs., 7 figs., 2 tabs.

  16. Nanostructures of Mg0.65Ti0.35Dx studied with x-ray diffraction, neutron diffraction, and magic-angle-spinning H2 NMR spectroscopy

    Science.gov (United States)

    Srinivasan, S.; Magusin, P. C. M. M.; Kalisvaart, W. P.; Notten, P. H. L.; Cuevas, F.; Latroche, M.; van Santen, R. A.

    2010-02-01

    Magnesium transition-metal alloys have a high hydrogen-storage capacity and show improved hydrogen-uptake and -release kinetics compared to magnesium alone. In the present study we have investigated the structure of bulk magnesium-titanium deuteride Mg0.65Ti0.35Dx prepared via mechanical alloying and gas-phase deuterium absorption by combined use of x-ray diffraction (XRD), neutron diffraction, and magic-angle-spinning H2 nuclear magnetic resonance (NMR). The initial ball-milled alloy has two XRD-distinct Mg and Ti fcc phases. Even after prolonged exposure to deuterium gas at 75 bar and 175°C the materials with and without palladium catalyst are only partly deuterated. Deuterium loading causes the formation of, on the one hand, bct (rutile) MgD2 nanodomains with interdispersed TiDy layers and, on the other hand, a separate fcc (fluorite) TiDz phase. The TiDy phase is XRD invisible, but shows clearly up at a H2 NMR shift of -43ppm between the shift of MgD2 (3 ppm) and the Knight shift of the TiDz phase (-143ppm) . Exchange NMR indicates complete deuterium exchange at 25°C between the MgD2 and TiDy phase within 1 s, as consistent with intimate contacts between these phases. Combined analysis of the XRD and NMR peak areas suggests that the deuterium concentrations y and z in the TiDy and TiDz domains are about 1.5 and 2.0, respectively. Comparing the intrinsic cell parameters of rutile MgH2 and fluorite TiH2 , we propose that stabilization of the mixed nanocomposite may arise from a coherent coupling between the crystal structures of the rutile MgD2 nanodomains and the thin layers of fcc TiDy .

  17. Atomic ordering and systematics of bonding lengths in the Ti-V omega phase: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Benites, G.M.; Guillermet, A.F. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche (Argentina); Aurelio, G. [Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquen (Argentina); Cuello, G.J.; Bermejo, F.J. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas y Tecnicas, Serrano 123, Madrid E-28006 (Spain)

    1999-03-04

    A new model describing the structural and bonding properties of the omega ({Omega}) phase in Zr-Nb alloys has recently been presented [12]. This model, which was aimed at explaining the composition dependence of the bonding lengths, predicts that the {Omega} phase is ordered, i.e., that some crystallographic sites are preferentially occupied by Zr atoms. Such feature, which should in principle be observed in other, related {Omega} phases, has not yet been tested against direct measurements. This problem has now been studied in the Ti-V system, which is the analogue of Zr-Nb in the 3d-transition series. Neutron diffraction measurements have been performed in quenched Ti-V alloys with V contents between 14 and 17 at.%. The diffraction spectra have been analysed using the Rietveld method, and a systematic analysis is reported here of the possibility of deviations from the random occupation of the two sublattices which are distinguished in the {Omega} structure. In addition, these new diffraction data are used in an evaluation of the shortest interatomic distances which are relevant for a comparison with the predictions of the model of Grad et al. (orig.) 28 refs.

  18. High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures.

    Science.gov (United States)

    Jacobsen, Matthew K; Ridley, Christopher J; Bocian, Artur; Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry; Azuma, Masaki; Attfield, J Paul; Kamenev, Konstantin V

    2014-04-01

    Pressure generation at cryogenic temperatures presents a problem for a wide array of experimental techniques, particularly neutron studies due to the volume of sample required. We present a novel, compact pressure cell with a large sample volume in which load is generated by a bellow. Using a supply of helium gas up to a pressure of 350 bar, a load of up to 78 kN is generated with leak-free operation. In addition, special fiber ports added to the cryogenic center stick allow for in situ pressure determination using the ruby pressure standard. Mechanical stability was assessed using finite element analysis and the dimensions of the cell have been optimized for use with standard cryogenic equipment. Load testing and on-line experiments using NaCl and BiNiO3 have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

  19. High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures

    Science.gov (United States)

    Jacobsen, Matthew K.; Ridley, Christopher J.; Bocian, Artur; Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry; Azuma, Masaki; Attfield, J. Paul; Kamenev, Konstantin V.

    2014-04-01

    Pressure generation at cryogenic temperatures presents a problem for a wide array of experimental techniques, particularly neutron studies due to the volume of sample required. We present a novel, compact pressure cell with a large sample volume in which load is generated by a bellow. Using a supply of helium gas up to a pressure of 350 bar, a load of up to 78 kN is generated with leak-free operation. In addition, special fiber ports added to the cryogenic center stick allow for in situ pressure determination using the ruby pressure standard. Mechanical stability was assessed using finite element analysis and the dimensions of the cell have been optimized for use with standard cryogenic equipment. Load testing and on-line experiments using NaCl and BiNiO3 have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

  20. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX/sub 2/ (X = Ru, Rh, Ir, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.; Haelg, W.; Kaldis, E.; Greidanus, F.J.A.M.; Buschow, K.H.J.

    1982-01-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield <100> as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu/sub 2/ type Laves phase systems PrX/sub 2/ (X = Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  1. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX2 (X=Ru, Rh, Ir, Pt)

    Science.gov (United States)

    Fischer, P.; Hälg, W.; Kaldis, E.; Greidanus, F. J. A. M.; Buschow, K. H. J.

    1982-09-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu2 type Laves phase systems PrX2 (X=Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  2. The character and application of a neutron imaging plate (NIP)

    Science.gov (United States)

    Karasawa, Y.; Kumazawa, S.; Miimura, N.

    We have developed a neutron imaging plate (NIP) as a new neutron detector and already reported the fundamental features of the NIP. The optimization of the NIP was carried out by changing a molar ratio of converter materials to PSL (Photostimulated luminescence) materials and thickness of the NIP. Some problems such as γ-ray sensitivity and irradiation effect for the practical use of the NIP were discussed. Several examples of application of the NIP were introduced.

  3. Application of hydrogel system for neutron attenuation

    CERN Document Server

    Gupta, S C; Gupta, B P

    2000-01-01

    Hydrogel sheets based on poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc) have been prepared by the technique of acetalization of PVA using formaldehyde and grafting of acrylic acid onto PVAc by gamma irradiation. PVA hydrogel (PVAB) sheets have been prepared in geometrically stable shapes by compression moulding process and characterised for their thermal properties, geometrical stability on water absorption, and neutron shielding efficiency. The effective protection from fast neutrons can be increased by a factor of 18% by swelling the PVAB sheets to 210% in water. The water intake and subsequent retention of water by the sheet can be tailored as per shielding requirements.

  4. Anomalous X-ray Diffraction Studies for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    2011-06-22

    Anomalous X-ray Diffraction (AXRD) has become a useful technique in characterizing bulk and nanomaterials as it provides specific information about the crystal structure of materials. In this project we present the results of AXRD applied to materials for photovoltaic applications: ZnO loaded with Ga and ZnCo{sub 2}O{sub 4} spinel. The X-ray diffraction data collected for various energies were plotted in Origin software. The peaks were fitted using different functions including Pseudo Voigt, Gaussian, and Lorentzian. This fitting provided the integrated intensity data (peaks area values), which when plotted as a function of X-ray energies determined the material structure. For the first analyzed sample, Ga was not incorporated into the ZnO crystal structure. For the ZnCo{sub 2}O{sub 4} spinel Co was found in one or both tetrahedral and octahedral sites. The use of anomalous X-ray diffraction (AXRD) provides element and site specific information for the crystal structure of a material. This technique lets us correlate the structure to the electronic properties of the materials as it allows us to probe precise locations of cations in the spinel structure. What makes it possible is that in AXRD the diffraction pattern is measured at a number of energies near an X-ray absorption edge of an element of interest. The atomic scattering strength of an element varies near its absorption edge and hence the total intensity of the diffraction peak changes by changing the X-ray energy. Thus AXRD provides element specific structural information. This method can be applied to both crystalline and liquid materials. One of the advantages of AXRD in crystallography experiments is its sensitivity to neighboring elements in the periodic tables. This method is also sensitive to specific crystallographic phases and to a specific site in a phase. The main use of AXRD in this study is for transparent conductors (TCs) analysis. TCs are considered to be important materials because of their

  5. Neutron emission in neutral beam heated KSTAR plasmas and its application to neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Jong-Gu, E-mail: jgkwak@nfri.re.kr; Kim, H.S.; Cheon, M.S.; Oh, S.T.; Lee, Y.S.; Terzolo, L.

    2016-11-01

    Highlights: • We measured the neutron emission from KSTAR plasmas quantitatively. • We confirmed that neutron emission is coming from neutral beam-plasma interactions. • The feasibility study shows that the fast neutron from KSTAR could be used for fast neutron radiography. - Abstract: The main mission of Korea Superconducting Tokamak Advanced Research (KSTAR) program is exploring the physics and technologies of high performance steady state Tokamak operation that are essential for ITER and fusion reactor. Since the successful first operation in 2008, the plasma performance is enhanced and duration of H-mode is extended to around 50 s which corresponds to a few times of current diffusion time and surpassing the current conventional Tokamak operation. In addition to long-pulse operation, the operational boundary of the H-mode discharge is further extended over MHD no-wall limit(β{sub N} ∼ 4) transiently and higher stored energy region is obtained by increased total heating power (∼6 MW) and plasma current (I{sub p} up to 1 MA for ∼10 s). Heating system consists of various mixtures (NB, ECH, LHCD, ICRF) but the major horse heating resource is the neutral beam(NB) of 100 keV with 4.5 MW and most of experiments are conducted with NB. So there is a lot of production of fast neutrons coming from via D(d,n){sup 3}He reaction and it is found that most of neutrons are coming from deuterium beam plasma interaction. Nominal neutron yield and the area of beam port is about 10{sup 13}–10{sup 14}/s and 1 m{sup 2} at the closest access position of the sample respectively and neutron emission could be modulated for application to the neutron radiography by varying NB power. This work reports on the results of quantitative analysis of neutron emission measurements and results are discussed in terms of beam-plasma interaction and plasma confinement. It also includes the feasibility study of neutron radiography using KSTAR.

  6. Neutron diffraction investigations of zero-field and field-induced magnetic structures of DyNiSn single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murogaki, K. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)]. E-mail: murogaki@fiberbit.net; Kawano, S. [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan); Andoh, Y. [Faculty of Regional Sciences, Tottori University, Tottori 680-8551 (Japan); Takahashi, M. [Institute of Materials Science, University of Tsukuba, Ibaraki 305-8573 (Japan); Kurisu, M. [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Nakamoto, G. [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Anh, D.T. Kim [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Tsutaoka, T. [Graduate School of Education, Hiroshima University, Hiroshima 739-8524 (Japan)

    2006-02-09

    Single crystal neutron diffraction studies have been performed on the rare-earth ternary compound, DyNiSn. This crystal exhibits an incommensurate magnetic structure expressed by the propagation vector, Q = (0.662 0.352 0) with its third harmonics at low temperatures. In an external magnetic field applied along the c-axis DyNiSn shows incommensurate modulation with Q = (1 0.315 0) at 1.6 K, while along the easy magnetization direction of the b-axis a commensurate modulation with Q = (2/3 0 0) develops at 2 K. The results along the b-axis are fully consistent with the magnetization curve.

  7. Neutron diffraction studies of R{sub 2}RhSi{sub 3} (R=Dy, Ho, Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bazela, W.; Penc, B.; Stuesser, N.; Szytula, A.; Wawrzynska, E.; Zygmunt, A

    2004-07-15

    Powder neutron diffraction and magnetic measurements have been carried out on R{sub 2}RhSi{sub 3} (R=Dy, Ho and Er) compounds at low temperatures. These compounds crystallize in a derivative of the hexagonal AlB{sub 2}-type structure and are antiferromagnets with the Neel temperatures equal to: 6.3 K for R=Dy, 5.2 K for R=Ho and 5 K for R=Er. Below these temperatures the magnetic order is described by the propagation vector: k=(0,0,((1)/(2))) for R=Dy, k=(((1)/(2)),0,0) for R=Ho and k=(0,0,0) for R=Er. This magnetic order is stable in the temperature range between 1.5 K and the Neel temperature.

  8. The metal-insulator transition of RNiO{sub 3} perovskites. What can we learn from neutron diffraction?

    Energy Technology Data Exchange (ETDEWEB)

    Medarde, M.L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    RNiO{sub 3} perovskites (R = rare earth) provide a remarkable opportunity to study the relationship between structural and physical properties since by moving along the 4f rare earth series, the evolution of several transport and magnetic properties can be nicely correlated to the steric effects associated with the lanthanide contraction. The most appealing example is probably the metal-insulator transition discovered for the compounds with R{ne}La, whose critical temperature T{sub M-I} increases with decreasing size of the rare earth ion. In this lecture, a summary of the most relevant neutron diffraction results on this system is presented. Moreover, the nickelates are used as an example to illustrate the performance of the diffractometers HRPT and DMCG to be installed at the SINQ. (author) 12 figs., 2 tabs., 17 refs.

  9. Magnetic structure of Pr6Fe13Ge studied by M(o)ssbauer effect and neutron diffraction

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Magnetic structure of Pr6Fe13Ge at room temperature has been investigated by magnetic measurement, M ssbauer effect and neutron diffraction. Magnetic atoms are closely packed up and down the mirror planes at z=0 and 1/2 and separated by the non-magnetic atoms located on the planes at z=1/4 and 3/4, which constructs an M/NM/M sandwich structure (M: magnetic, NM: non-magnetic). The intralayer magnetic moments couple ferromagnetically and are out of ab plane at a small angle so as to form a component along c-axis. The interlayer coupling is antiferromagnetic for the ab component while ferromagnetic for the c component.

  10. Determination of the magnetic structure of CePt2In7 by means of neutron diffraction

    Science.gov (United States)

    Raba, M.; Ressouche, E.; Qureshi, N.; Colin, C. V.; Nassif, V.; Ota, S.; Hirose, Y.; Settai, R.; Rodière, P.; Sheikin, I.

    2017-04-01

    The magnetic structure of the heavy fermion antiferromagnet CePt2In7 is determined using neutron diffraction. We find a magnetic wave vector qM=(1 /2 ,1 /2 ,1 /2 ) , which is temperature independent up to TN=5.5 K. A staggered moment of 0.45 (1 ) μB at 2 K resides on the Ce ion. The nearest-neighbor moments in the tetragonal basal plane are aligned antiferromagnetically. The moments rotate by 90∘ from one CeIn3 plane to another along the c axis. A much weaker satellite peak with an incommensurate magnetic wave vector qM=(1 /2 ,1 /2 ,0.47 ) seems to develop at low temperature. However, the experimental data available so far are not sufficient to draw a definitive conclusion about the possible coexistence of commensurate and incommensurate magnetic structures in this material.

  11. Structure Refinement of (Sr,BaNb2O6 Ceramic Powder from Neutron and X-Rays Diffraction Data

    Directory of Open Access Journals (Sweden)

    J.G. Carrio

    2002-03-01

    Full Text Available The structure of polycrystalline strontium barium niobate at room temperature was refined by the Rietveld method. Sintered ceramic samples were used to collect powder neutron and X-ray diffraction data. The ratio Sr/Ba ~ 64/36 was found from the initial batch composition Sr0.61Ba0.39Nb2O6, corroborating with the quantitative X-ray dispersive spectroscopy (EDS measurements. The structure is tetragonal with cell parameters a, b = 12.4504(3 Å and c = 3.9325(1 Å and space group P4bm. It was not necessary to introduce any positional disorder for the oxygen atoms. Cation Nb+5 displacements not parallel to the c direction are presented, which can influence the behavior of the ferroelectric properties.

  12. Evolution of the magnetic order in the Ho(Mn, Al) sub 2 system; neutron diffraction study

    CERN Document Server

    Golosovsky, I V; Markosyan, A S; Roisnel, T

    2002-01-01

    The neutron diffraction study of Ho(Mn sub 1 sub - sub x Al sub x) sub 2 shows the coexistence of two cubic Laves phases with different unit-cell parameters and substantially different magnetic behaviours. The first phase combines ordered ferrimagnetic and disordered antiferromagnetic components of the magnetic moments. With increasing Al content, starting from the long-range ferrimagnetic order with the induced Mn moment in HoMn sub 2 , the progressive formation of spontaneous Mn moments yields short-range order, which in turn transforms to ferromagnetic order in HoAl sub 2. The second phase with incommensurate magnetic structure is driven by the spontaneous Mn moments and exists only over limited ranges of Al content and unit-cell parameter. It has a finite correlation length and appears from a second-order transition without a magneto-volume effect.

  13. Re-investigation of yttria-tetragonal zirconia polycrystal (Y-TZP) by neutron powder diffraction - a cautionary tale

    Energy Technology Data Exchange (ETDEWEB)

    Argyriou, D.N. [Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia); Howard, C.J. [Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia)

    1995-04-01

    In the re-investigation by neutron powder diffraction of 3 mol% yttria-tetragonal zirconia polycrystal (Y-TZP), it was realized that the sample, initially taken to be single-phase tetragonal zirconia, was in fact a two-phase mixture of the tetragonal (80%) and cubic (20%) polymorphs. Two-phase refinement gave for the tetragonal phase [P4{sub 2}/nmc, a = 3.6008 (1), c = 5.1793 (1) A] the results z{sub O} = 0.4564 (1), B{sub Zr,Y} = 0.45 (2) and B{sub O} = 0.72 (2) A{sup 2}. Refinement on the basis of a single-phase tetragonal sample yielded values for the position and displacement parameters somewhat biased towards those pertaining to the cubic phase. The conclusions from previous studies have been re-examined in the light of the present work. (orig.).

  14. Neutron diffraction observations of ferroelastic domain switching and tetragonal-to-monoclinic transformation in Ce-TZP

    Energy Technology Data Exchange (ETDEWEB)

    Kisi, E.H. [Univ. of Newcastle, Callaghan, New South Wales (Australia). Dept. of Mechanical Engineering; Kennedy, S.J.; Howard, C.J. [Australian Nuclear Science and Technology Organisation, Menai, New South Wales (Australia). Neutron Scattering Group

    1997-03-01

    In-situ neutron diffraction has been used to study the plastic deformation of a tetragonal zirconia polycrystal stabilized with 12 mol% ceria under compressive loads up to 1.6 GPa. The development of significant plastic strain in the ceramic has been found to be due to a combination of ferroelastic switching and the tetragonal-to-monoclinic phase transformation, both beginning at {approximately}1.2 GPa. Evidence of a strong coupling between the two phenomena is present. Both transitions are partially reversed on removal of the load. The linear elastic response of the a and c crystal axes of the parent tetragonal phase suggests that the ferroelastic switching occurs directly by a shear mechanism rather than via a cubic intermediate state. Anisotropic distortion of the tetragonal unit cell, as the critical stress is approached, gives some insight into the shear transformation mechanisms.

  15. Neutron diffraction study of quantum effects on the pair correlation function of low-density {sup 4}He

    Energy Technology Data Exchange (ETDEWEB)

    Guarini, E. [Istituto Nazionale per la Fisica della Materia, Unita di Ricerca di Firenze, Polo Scientifico Universita di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Barocchi, F. [Istituto Nazionale per la Fisica della Materia, Unita di Ricerca di Firenze, Polo Scientifico Universita di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Dipartimento di Fisica, Polo Scientifico Universita di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Celli, M.; Zoppi, M. [Istituto Nazionale per la Fisica della Materia, Unita di Ricerca di Firenze, Polo Scientifico Universita di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Istituto di Fisica Applicata ' ' Nello Carrara' ' , Consiglio Nazionale delle Ricerche, via Panciatichi 56/30, 50127 Firenze (Italy); Fischer, H.E. [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Magli, R. [Istituto Nazionale per la Fisica della Materia, Unita di Ricerca di Firenze, Polo Scientifico Universita di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Dipartimento di Chimica e Biochimica Medica, Universita di Milano, LITA, via F. lli Cervi 93, 20090 Segrate Milano (Italy)

    2002-07-01

    An extensive neutron diffraction investigation on low-density (n<4.35 nm{sup -3}) states of helium gas along the 6-K isotherm has been performed by means of both wide- and small-angle experiments, allowing for the extraction of the zero- and first-order density coefficients of c(k), the Fourier transform of the direct correlation function, in a very wide wavevector region extending from k=1 nm{sup -1} to k=160 nm{sup -1}. The two independent measurements provide quantitatively consistent results, and the experimental quantities show a good agreement with the thermodynamic (i.e. k=0) data. The comparison of the experimental pure two-body correlation with the corresponding result of a classical calculation clearly indicates the need of a quantum-mechanical approach. (orig.)

  16. Neutron diffraction and thermal studies of amorphous CS{sub 2} realised by low-temperature vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yamamuro, O.; Matsuo, T. [Osaka Univ., Dept. of Chemistry, Graduate School of Sciences (Japan); Onoda-Yamamuro, N. [Tokyo Denki Univ., College of Sciences and Technology (Japan); Takeda, K. [Naruto Univ., Dept. of Chemistry, Tokushima (Japan); Munemura, H.; Tanaka, S.; Misawa, M. [Niigata Univ. (Japan). Faculty of Science

    2003-08-01

    We have succeeded in preparing amorphous carbon disulphide (CS{sub 2}) by depositing its vapour on a cold substrate at 10 K. Complete formation of the amorphous state has been confirmed by neutron diffraction and differential thermal analysis (DTA). The amorphous sample crystallized at ca. 70 K, which is lower than the hypothetical glass transition temperature (92 K) estimated from the DTA data of the (CS{sub 2}){sub x}(S{sub 2}Cl{sub 2}){sub 1-x} binary mixture. CS{sub 2}, a symmetric linear tri-atomic molecule, is the simplest of the amorphized molecular substances whose structural and thermal information has been reported so far. Comparison of the static structure factors S(Q) has shown that the orientational correlation of CS{sub 2} molecules may be much stronger in the amorphous state than in the liquid state at higher temperature. (authors)

  17. Separate determination of the amplitude of thermal vibrations and static atomic displacements in titanium carbide by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S. [Uzbekistan Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

    2011-05-15

    The amplitude of thermal (dynamic) atomic vibrations and meansquare static atomic displacements in titanium carbide TiC{sub x} (x = 0.97, 0.88, 0.70) have been separately determined by measuring neutron diffraction patterns at two temperatures (T{sub 1} = 300 K and T{sub 2} = 80 K). The static lattice distortions in stoichiometric titanium carbide are experimentally found to be negligible. In the TiC{sub x} homogeneity range, the amplitude {radical}u{sup 2}{sub dyn} of thermal atomic vibrations significantly increases with a decrease in the carbon concentration. The Debye temperature has been determined for the first time in the TiC{sub x} homogeneity range at both room and liquid-nitrogen temperatures.

  18. In-situ neutron diffraction of LaCoO3 perovskite under uniaxial compression. II. Elastic properties

    Science.gov (United States)

    Lugovy, Mykola; Aman, Amjad; Chen, Yan; Orlovskaya, Nina; Kuebler, Jakob; Graule, Thomas; Reece, Michael J.; Ma, Dong; Stoica, Alexandru D.; An, Ke

    2014-07-01

    Calculations of elastic constants and development of elastic anisotropy under uniaxial compression in originally isotropic polycrystalline LaCoO3 perovskite are reported. The lattice strains in individual (hkl) planes as well as average lattice strain were determined both for planes oriented perpendicular and parallel to the loading direction using in-situ neutron diffraction. Utilizing average lattice strains as well as lattice strains along the a and c crystallographic directions, an attempt was made to determine Poisson's ratio of LaCoO3, which was then compared with that measured using an impulse excitation technique. The elastic constants were calculated and Young's moduli of LaCoO3 single crystal in different crystallographic directions were estimated.

  19. Monoclinic β-Li2TiO3: Neutron diffraction study and estimation of Li diffusion pathways

    Science.gov (United States)

    Monchak, M.; Dolotko, O.; Mühlbauer, M. J.; Baran, V.; Senyshyn, A.; Ehrenberg, H.

    2016-11-01

    A neutron powder diffraction study on lithium titanate Li2TiO3 was performed at low temperatures. The monoclinic β-phase has been found to be stable over the whole investigated range of temperatures (4 K-300 K). A smooth and nonlinear increase of the lattice parameters has been observed upon heating and correlated to the behavior of interatomic distances. Lithium diffusion pathways in Li2TiO3 were estimated theoretically on the basis of the obtained structural data using bond-valence modeling. Experimentally diffusion pathways were evaluated by analysis of the negative nuclear scattering densities at 1073 K, which were reconstructed using a maximum entropy method. Although the bond-valence mismatch map indicated a possible Li diffusion either in ab plane or along c direction, analysis of the experimental data revealed that Li migration is thermodynamically less feasible in latter case.

  20. In-situ neutron diffraction of LaCoO{sub 3} perovskite under uniaxial compression. II. Elastic properties

    Energy Technology Data Exchange (ETDEWEB)

    Lugovy, Mykola [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Institute for Problems of Materials Science, Kiev 03142 (Ukraine); Aman, Amjad; Orlovskaya, Nina, E-mail: Nina.Orlovskaya@ucf.edu [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Chen, Yan [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Kuebler, Jakob; Graule, Thomas [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for High Performance Ceramics, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Reece, Michael J. [The School of Engineering and Materials Science, Queen Mary, University of London, London E1 4NS (United Kingdom); Ma, Dong; Stoica, Alexandru D.; An, Ke [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-07-07

    Calculations of elastic constants and development of elastic anisotropy under uniaxial compression in originally isotropic polycrystalline LaCoO{sub 3} perovskite are reported. The lattice strains in individual (hkl) planes as well as average lattice strain were determined both for planes oriented perpendicular and parallel to the loading direction using in-situ neutron diffraction. Utilizing average lattice strains as well as lattice strains along the a and c crystallographic directions, an attempt was made to determine Poisson's ratio of LaCoO{sub 3}, which was then compared with that measured using an impulse excitation technique. The elastic constants were calculated and Young's moduli of LaCoO{sub 3} single crystal in different crystallographic directions were estimated.

  1. Kartini Research Reactor prospective studies for neutron scattering application

    Energy Technology Data Exchange (ETDEWEB)

    Widarto [Yogyakarta Nuclear Research Center, BATAN (Indonesia)

    1999-10-01

    The Kartini Research Reactor (KRR) is located in Yogyakarta Nuclear Research Center, Yogyakarta - Indonesia. The reactor is operated for 100 kW thermal power used for research, experiments and training of nuclear technology. There are 4 beam ports and 1 column thermal are available at the reactor. Those beam ports have thermal neutron flux around 10{sup 7} n/cm{sup 2}s each other and used for sub critical assembly, neutron radiography studies and Neutron Activation Analysis (NAA). Design of neutron collimator has been done for piercing radial beam port and the calculation result of collimated neutron flux is around 10{sup 9} n/cm{sup 2}s. This paper describes experiment facilities and parameters of the Kartini research reactor, and further more the prospective studies for neutron scattering application. The purpose of this paper is to optimize in utilization of the beam ports facilities and enhance the manpower specialty. The special characteristic of the beam ports and preliminary studies, pre activities regarding with neutron scattering studies for KKR is presented. (author)

  2. Compact, energy EFFICIENT neutron source: enabling technology for various applications

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, A.; Roser, T.

    2009-12-01

    A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.

  3. Resolution of crystal structures by X-ray and neutrons powder diffraction using global optimisation methods; Resolution des structures cristallines par diffraction des rayons X et neutrons sur poudres en utilisant les methodes d'optimisation globale

    Energy Technology Data Exchange (ETDEWEB)

    Palin, L

    2005-03-15

    We have shown in this work that X-ray diffraction on powder is a powerful tool to analyze crystal structure. The purpose of this thesis is the resolution of crystal structures by X-ray and neutrons diffraction on powder using global optimisation methods. We have studied 3 different topics. The first one is the order-disorder phenomena observed in some globular organic molecular solids. The second is the opiate family of neuropeptides. These neurotransmitters regulate sensory functions including pain and control of respiration in the central nervous system. The aim of our study was to try to determine the crystal structure of Leu-enkephalin and some of its sub-fragments. The determination of the crystal structures has been done performing Monte Carlo simulations. The third one is the location of benzene in a sodium-X zeolite. The zeolite framework was already known and the benzene has been localized by simulated annealing and by the use of maximum entropy maps.

  4. Applications of neutron scattering to heterogeneous catalysis

    Science.gov (United States)

    Parker, Stewart F.; Lennon, David

    2016-09-01

    Historically, most studies of heterogeneous catalysts that have used neutron vibrational spectroscopy have employed indirect geometry instruments with a low (methane to synthesis gas (CO + H2) over Ni/Al2O3 catalysts and an operando study of CO oxidation. We conclude with a proposal for a unique instrument that combines both indirect and direct geometry spectrometers.

  5. Gamma-ray and neutron diffraction studies of CoF2: magnetostriction, electron density and magnetic moments.

    Science.gov (United States)

    Jauch, W; Reehuis, M; Schultz, A J

    2004-01-01

    Accurate structure factors up to sin theta/lambda = 1.6 A(-1) have been measured with 316.5 keV gamma-rays from CoF(2), both at room temperature and in the antiferromagnetic state at 10 K. The same crystal was used to collect extended time-of-flight neutron diffraction data in the two magnetic states, which allowed an accurate determination of the fluorine positional parameter. For room temperature, the standard structural parameters are reported. At 10 K, a complete charge-density study has been carried out. The total number of 3d electrons on Co is found to be 6.95 (3). The experimental populations of the d orbitals agree with expectation from crystal field theory. The fluorine valence region exhibits a strong dipolar deformation. Electronic properties at the bond critical points and integrated atomic properties are derived from the static model electron density, revealing the Co-F interactions as purely ionic. On magnetic ordering, a shift of the fluorine ions of 1.5 (4) x 10(-3) A is found which confirms a prediction from theory of optical birefringence. The effect of magnetostriction on the distortion of the ligand coordination octahedra is compared for the late members of the 3d transition-metal difluorides. From neutron powder diffraction, an ordered magnetic moment of 2.60 (4) mu(B) per cobalt ion is found. Despite the strong deviation from the ideal spin value of 3 mu(B), there is still an appreciable orbital contribution to the local magnetic moment.

  6. Production, Distribution, and Applications of Californium-252 Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    reencapsulators domestically and internationally. Sealed {sup 252}Cf sources are also available for loan to agencies and subcontractors of the U.S. government and to universities for educational, research, and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of {sup 252}Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments, and irradiation of rice to induce genetic mutations.

  7. Charge localization in oxidized Pb2Sr2Y0.5Cu308+8 studies by electron and neutron powder diffraction

    DEFF Research Database (Denmark)

    Iversen, M.H.; Jørgensen, J.E.; Andersen, N.H.

    1998-01-01

    Oxidized Pb2Sr2Y0.5Ca0.5Cu3O8+delta was studied by electron diffraction and neutron powder diffraction. The electron diffraction diagrams showed a doubling along the b-axis and a quadruplication along the a-axis indicating that the excess oxygen is incorporated into the structure in an ordered wa...... of superconductivity in the oxidized compound. (C) 1998 Elsevier Science B.V.......Oxidized Pb2Sr2Y0.5Ca0.5Cu3O8+delta was studied by electron diffraction and neutron powder diffraction. The electron diffraction diagrams showed a doubling along the b-axis and a quadruplication along the a-axis indicating that the excess oxygen is incorporated into the structure in an ordered way....... The oxygen content was determined from refinement of the neutron data and delta = 1.2(1) was obtained. Calculation of bond valency sums for the cations shows that the bond valency sum for Cu in the CuO2 layers in Pb2Sr2Y0.5Ca0.5Cu3O8 decreases when the compound is oxidized, thereby explaining the lack...

  8. Studies of medium-range correlations by small-/wide-angle neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Otomo, Toshiya; Kamiyama, Takashi; Furusaka, Michihiro [Institute of Material Structure Science Lab., Neutron Science Lab., Tsukuba, Ibaraki (Japan); Kanno, Ryoji [Tokyo Institute of Technology, Dept. of Electronic Chemistry, Yokohama, Kanagawa (Japan); Yamamuro, Osamu [Osaka Univ., Graduate School of Science, Dept. of Chemistry and Microcalorimetry Research Center, Toyonaka, Osaka (Japan)

    2002-01-01

    A small/wide-angle neutron diffractometers (SWAN) covers very wide Q-range, 0.007A{sup -1} to 12A{sup -1}, therefore this instrument is useful to investigate medium-range correlations in many materials, including biological materials. Two examples are here to show the usefulness of the wide Q-range measurements to understand Li-absorption mechanism in hard-carbon as a battery anode material and to investigate medium-range correlation in vapor deposited CCl{sub 4} glass system. (author)

  9. Magnetic Structure of Tb-Tm Alloys Studied by Neutron Diffraction

    DEFF Research Database (Denmark)

    Hansen, P.; Lebech, Bente

    1976-01-01

    Single crystals of Tb-Tm alloys with Tm contents of 12%, 40%, 55% and 65% were investigated by neutron diffractometry over the temperature range 4.2-300K. All these alloys order magnetically to a basal plane spiral below the Neel temperature. Below the Curie temperature the magnetic ordering of t...... is modulated along the c axis (CAM structure). Tb-Tm alloys have an inhomogeneous phase, where the spins associated with the Tb ions lie in the basal plane, while the spins associated with the Tm ions order along the c axis....

  10. A method for detailed simulations of neutron diffraction from imperfect crystals

    Energy Technology Data Exchange (ETDEWEB)

    Alianelli, L. E-mail: lucia.alianelli@ill.fr; Wilson, N.; Andersen, K.H.; Sanchez del Rio, M.; Felici, R

    2004-08-21

    An upgraded version of the McStas Monochromator-curved module is presented. The new component, called Monochromator-reflect, is based on the use of input files for interpolating the neutron reflection and transmission probabilities according to the theoretical reflectivity of the crystal. These probabilities depend on the energy and angle at the crystal surface and also on the crystal mosaicity, geometry, material scattering cross-section, attenuation coefficient, and Bragg planes. We present details of the algorithm and definitions which are essential for a correct use of the module and show the improvements that it offers.

  11. A method for detailed simulations of neutron diffraction from imperfect crystals

    Science.gov (United States)

    Alianelli, L.; Wilson, N.; Andersen, K. H.; Sánchez del Río, M.; Felici, R.

    2004-08-01

    An upgraded version of the McStas Monochromator-curved module is presented. The new component, called Monochromator-reflect, is based on the use of input files for interpolating the neutron reflection and transmission probabilities according to the theoretical reflectivity of the crystal. These probabilities depend on the energy and angle at the crystal surface and also on the crystal mosaicity, geometry, material scattering cross-section, attenuation coefficient, and Bragg planes. We present details of the algorithm and definitions which are essential for a correct use of the module and show the improvements that it offers.

  12. High temperature phase stability in Li0.12Na0.88NbO3: A combined powder X-ray and neutron diffraction study

    Science.gov (United States)

    Mishra, S. K.; Krishna, P. S. R.; Shinde, A. B.; Jayakrishnan, V. B.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

    2015-09-01

    The phase stabilities of ecofriendly piezoelectric material of lithium doped sodium niobate for composition Li0.12Na0.88NbO3 (LNN12) have been investigated by a combination of powder X-ray and neutron diffraction techniques in the temperature range of 300-1100 K. We observed interesting changes with appearance or disappearance of the super-lattice reflections in the powder diffraction patterns. Unambiguous experimental evidence is shown for coexistence of paraelectric and ferroelectric orthorhombic phases in the temperature range of 525 K to 675 K. We identified the correct crystal structure of LNN12 with temperature and correlated it with observed anomaly in the physical properties. Identification of crystal structure also helps in the mode assignments in Raman and infrared spectroscopies. We argued that application of chemical pressure as a result of Li substitution in NaNbO3 matrix favors the freezing of zone centre phonons in contrast to the freezing of zone boundary phonons in pure NaNbO3 with the variation of temperature.

  13. Neutron diffraction study of Er2Fe15A12 and Er2Fe12A15

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The crystallographic and magnetic structures of Er2Fe15Al2 and Er2Fe12Al5 have been refined in Gaussian peak-shape by Rietveld analysis of Neutron diffraction data. The refined results indicated that Er2Fe15Al2 compound has Th2Ni17-typc hexagonal structure (space group: P63/mmc) and Er2Fe12Al5 has Th2Zn17-type rhombohedral structure (space group:R 3m). The Al atoms prefer 12j and 12k sites with ccupancies 0.21 and 0.13, respectively, in Er2Fe15Al2 and prefer 18f, 18h and 6c sites with occupancies 0.35, 0.36 and 0.37, respectively, in Er2Fe12Al5. The magnetic moments of all Fe atoms display ferromagnetically arrangement and the moments of Er atoms couple ferrimagnetically to the moments of the Fe atoms. The moments lie in the plane perpendicular to the six-fold axis and exhibit planar magnetic anisotropy in both samples. The values of Tc were given and the neutron refined results coincide with that of the magnetic measurements. The relation between magnetic properties and structures was discussed.

  14. Hemoglobin redux: combining neutron and X-ray diffraction with mass spectrometry to analyse the quaternary state of oxidized hemoglobins.

    Science.gov (United States)

    Mueser, Timothy C; Griffith, Wendell P; Kovalevsky, Andrey Y; Guo, Jingshu; Seaver, Sean; Langan, Paul; Hanson, B Leif

    2010-11-01

    Improvements in neutron diffraction instrumentation are affording the opportunity to re-examine the structures of vertebrate hemoglobins and to interrogate proton and solvent position changes between the different quaternary states of the protein. For hemoglobins of unknown primary sequence, structural studies of cyanomethemoglobin (CNmetHb) are being used to help to resolve sequence ambiguity in the mass spectra. These studies have also provided additional structural evidence for the involvement of oxidized hemoglobin in the process of erythrocyte senescence. X-ray crystal studies of Tibetan snow leopard CNmetHb have shown that this protein crystallizes in the B state, a structure with a more open dyad, which possibly has relevance to RBC band 3 protein binding and erythrocyte senescence. R-state equine CNmetHb crystal studies elaborate the solvent differences in the switch and hinge region compared with a human deoxyhemoglobin T-state neutron structure. Lastly, comparison of histidine protonation between the T and R state should enumerate the Bohr-effect protons.

  15. Visualizing the structural evolution of LSM/xYSZ composite cathodes for SOFC by in-situ neutron diffraction.

    Science.gov (United States)

    Chen, Yan; Yang, Ling; Ren, Fei; An, Ke

    2014-06-05

    Thermal stability of composite cathodes for solid oxide fuel cells, the mixtures of (La0.8Sr0.2)0.95MnO(3-δ) (LSM) and (Y2O3)(x)(ZrO2)(1-x) (xYSZ, x = 3, 6, 8 and 10), is determined using in-situ neutron diffraction. Thanks to the most advanced high flux neutron source, our work highlights the visualization of the phase evolutions in heterogeneous material systems at high temperatures, along with the analysis of the diffusion activities of transition metal ions that reveal the reaction mechanism and kinetics. It is found that the tetragonal-to-cubic phase transition in YSZ at T > 900°C leads to a heterogeneous redistribution of Mn ions. The subsequent reaction of LSM and YSZ occurring at T > 1100°C is revealed as a three-stage kinetic process, yielding La2Zr2O7, SrZrO3 and MnO. The diffusion activities of Y, Mn and La ions in the heterogeneous systems at elevated temperatures are derived by the structural analysis, and the three-stage reaction of YSZ and LSM is found strongly correlated to ions' behaviors as functions of temperature.

  16. Neutron and X-ray diffraction and empirical potential structure refinement modelling of magnesium stabilised amorphous calcium carbonate

    DEFF Research Database (Denmark)

    Cobourne, G.; Mountjoy, G.; Rodriguez Blanco, Juan Diego

    2014-01-01

    from CO3 molecules and 0.6 oxygen atoms from H2O molecules. The average CaO bond length is 2.40 Å. The distribution of Ca in the model is homogeneous with a uniformly distributed Ca-rich network and no evidence of the Ca-poor channels as previously reported for a reverse Monte Carlo model of ACC......Amorphous calcium carbonate (ACC) plays a key role in biomineralisation processes in sea organisms. Neutron and X-ray diffraction have been performed for a sample of magnesium-stabilised ACC, which was prepared with a Mg:Ca ratio of 0.05:1 and 0.25 H2O molecules per molecule of CO3. The empirical...... potential structure refinement method has been used to make a model of magnesium-stabilised ACC and the results revealed a fair agreement with the experimental diffraction data. The model has well-defined CO3 and H2O molecules. The average coordination number of Ca is 7.4 and is composed of 6.8 oxygen atoms...

  17. Decomposition of TiH{sub 2} studied in situ by synchrotron X-ray and neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, C., E-mail: catalina.jimenez@helmholtz-berlin.de [Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Garcia-Moreno, F.; Pfretzschner, B. [Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Klaus, M.; Wollgarten, M.; Zizak, I.; Schumacher, G.; Tovar, M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Banhart, J. [Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2011-09-15

    Graphical abstract: We found experimentally core-shell models to describe the decomposition processes of as-received and pre-oxidised TiH{sub 2} powders. A shell of the hcp hydrogen solid solution ({alpha}) controls the dehydrogenation of as-received TiH{sub 2}, while a TiO{sub 2} rutile shell controls the outgassing from the pre-oxidised powder. - Abstract: Decomposition during constant heating of as-received and pre-oxidized titanium hydride (TiH{sub 2}) powder under flowing and stationary Ar was studied in situ by synchrotron X-ray and neutron diffraction. Diffraction data were compared to corresponding thermoanalysis traces in order to relate peaks of H{sub 2} release with individual phase transformations. We found that every peak of H{sub 2} release is correlated with regimes of lattice parameter contraction. Core-shell models to describe the decomposition processes measured were found, and further verified by electron microscopy. The models show that a shell of the hexagonal close-packed hydrogen solid solution ({alpha}) around each particle core controls its dehydrogenation for as-received TiH{sub 2}, while a TiO{sub 2} rutile shell controls the outgassing from the pre-oxidized powder.

  18. Glycine zinc sulfate pentahydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction

    Directory of Open Access Journals (Sweden)

    A. Dominic Fortes

    2016-10-01

    Full Text Available Single crystals of glycine zinc sulfate pentahydrate [systematic name: hexaaquazinc tetraaquadiglycinezinc bis(sulfate], [Zn(H2O6][Zn(C2H5NO22(H2O4](SO42, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octahedra on sites of symmetry -1 and two SO4 tetrahedra with site symmetry 1; the octahedra comprise one [tetraaqua-diglycine zinc]2+ ion (centred on one Zn atom and one [hexaaquazinc]2+ ion (centred on the other Zn atom; the glycine zwitterion, NH3+CH2COO−, adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N—H...O hydrogen bonds between the amine and carboxylate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate internuclear X—H (X = N, O bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework.

  19. Work Hardening, Dislocation Structure, and Load Partitioning in Lath Martensite Determined by In Situ Neutron Diffraction Line Profile Analysis

    Science.gov (United States)

    Harjo, Stefanus; Kawasaki, Takuro; Tomota, Yo; Gong, Wu; Aizawa, Kazuya; Tichy, Geza; Shi, Zengmin; Ungár, Tamas

    2017-09-01

    A lath martensite steel containing 0.22 mass pct carbon was analyzed in situ during tensile deformation by high-resolution time-of-flight neutron diffraction to clarify the large work-hardening behavior at the beginning of plastic deformation. The diffraction peaks in plastically deformed states exhibit asymmetries as the reflection of redistributions of the stress and dislocation densities/arrangements in two lath packets: soft packet, where the dislocation glides are favorable, and hard packet, where they are unfavorable. The dislocation density was as high as 1015 m-2 in the as-heat-treated state. During tensile straining, the load and dislocation density became different between the two lath packets. The dislocation character and arrangement varied in the hard packet but hardly changed in the soft packet. In the hard packet, dislocations that were mainly screw-type in the as-heat-treated state became primarily edge-type and rearranged towards a dipole character related to constructing cell walls. The hard packet played an important role in the work hardening in martensite, which could be understood by considering the increase in dislocation density along with the change in dislocation arrangement.

  20. In-situ neutron diffraction study of phase stress evolutions in a Ni-basedporous anode under uniaxial load

    Energy Technology Data Exchange (ETDEWEB)

    An, Ke [ORNL; Clausen, B [Los Alamos National Laboratory (LANL); Stoica, Alexandru Dan [ORNL; Armstrong, Beth L [ORNL; Skorpenske, Harley David [ORNL; Brown, D. W. [Los Alamos National Laboratory (LANL); Wang, Xun-Li [ORNL

    2010-01-01

    Ni/YSZ porous composite is used widely as anode for solid oxide fuel cells. In this study, neutron diffraction patterns were recorded in-situ while a bulk porous Ni-NiO-YSZ anode was loaded under uniaxial compression. Single peak refinement was used to calculate the lattice strains of each phase in the composite, and the local stress state of each phase was derived from the measured lattice strains and the corresponding diffraction elastic constants. An internal triaxial stress state was observed to develop in the bulk of the specimen under plastic deformation, specifically in the Ni phase. Meanwhile, the NiO and YSZ phases are deforming elastically even in the macroscopically plastic regime of deformation. The von Mises equivalent stress was used to quantify the phase stress evolution. A significant stress concentration induced by the presence of pores becomes manifest in all three phase components. The reduction of stress concentration factor in Ni above the yield point of the composite can be attributed to a gradual change of the grains-pores morphology during the plastic deformation.

  1. Oxygen excess in La{sub 2}CoO{sub 4+{delta}}: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Aguadero, A.; Daza, L. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Madrid (Spain); Alonso, J.A. [Inst. de Ciencia de Materiales de Madrid, CSIC, Cantoblanco (Spain)

    2008-06-15

    The layered perovskite La{sub 2}CoO{sub 4+{delta}} has been prepared and characterized in order to identify its capability of incorporating interstitial oxygen atoms ({delta}) and their effect on the crystal structure. The synthesis has been performed by a citrate-nitrate soft-chemistry technique; a high oxygen pressure treatment (350 C, 200 bar) has allowed us to increment the interstitial oxygen contents up to {delta} = 0.32(1). The samples have been characterized by thermal analysis (TG and DTA), X-ray diffraction at room temperature and neutron diffraction at temperatures up to 600 C. At r. t., the as-prepared phase, La{sub 2}CoO{sub 4.22(1)}, is orthorhombic, space group Bmab, with an important orthorhombic strain, if compared with La{sub 2}NiO{sub 4+{delta}}. At high temperatures it undergoes two consecutive structural transitions, to an orthorhombic superstructure at 375 C and finally to a tetragonal symmetry (space group F4/mmm) al 590 C. The phase La{sub 2}CoO{sub 4.32(1)} seems to represent a superstructure with orthorhombic symmetry and with a doubled b unit-cell parameter with respect to the prepared sample. (orig.)

  2. Neutron diffraction study of quadruple perovskite SrCu{sub 3}Fe{sub 3}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Ikuya, E-mail: i-yamada@21c.osakafu-u.ac.jp [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Murakami, Makoto; Mori, Shigeo [Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Irifune, Tetsuo [Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan)

    2016-08-26

    The magnetic structure of the quadruple perovskite SrCu{sub 3}Fe{sub 4}O{sub 12} is studied by means of neutron powder diffraction. The magnetic diffraction peaks are observed at low temperatures below 200 K. The Rietveld refinement result suggests an antiferromagnetic alignment of Fe spin magnetic moments for SrCu{sub 3}Fe{sub 4}O{sub 12} at low temperature. The refined magnetic moment at 4 K is ∼3.5 µ{sub B}, which is larger than that of that of CeCu{sub 3}Fe{sub 4}O{sub 12} (2.3 µ{sub B}). The increase in the magnetic moment is attributed to the larger Fe{sup 3+}:Fe{sup 5+} ratio for SrCu{sub 3}Fe{sub 4}O{sub 12} (∼4:1) compared with that of CeCu{sub 3}Fe{sub 4}O{sub 12} (∼3:1).

  3. Neutron diffraction study of quasi-one-dimensional spin-chain compounds Ca3Co2−FeO6

    Indian Academy of Sciences (India)

    Anil Jain; S M Yusuf; Sher Singh

    2008-11-01

    We report the results of the DC magnetization, neutron powder diffraction and neutron depolarization studies on the spin-chain compounds Ca3Co2−FeO6 ( = 0, 0.1, 0.2 and 0.4). Rietveld refinement of neutron powder diffraction patterns at room temperature confirms the single-phase formation for all the compounds in rhombohedral structure with space group R$\\bar{3}$c. Rietveld refinement also confirms that Fe was doped at the trigonal prism site, 6a (0, 0, 1/4) of Co. The high temperature magnetic susceptibility obeys the Curie–Weiss law; the value of the paramagnetic Curie temperature () decreases as the concentration of iron increases and it becomes negative for = 0.4. No extra Bragg peak as well as no observable enhancement in the intensity of the fundamental (nuclear) Bragg peaks has been observed in the neutron diffraction patterns down to 30 K. No depolarization of neutron beam has been observed down to 3 K confirming the absence of ferro- or ferrimagnetic-like correlation.

  4. Structural and magnetic properties of inverse opal photonic crystals studied by x-ray diffraction, scanning electron microscopy, and small-angle neutron scattering

    NARCIS (Netherlands)

    Grigoriev, S.V.; Napolskii, K.S.; Grigoryeva, N.A.; Vasilieva, A.V.; Mistonov, A.A.; Chernyshov, D.Y.; Petukhov, A.V.; Belov, D.V.; Eliseev, A.A.; Lukashin, A.V.; Tretyakov, Y.D.; Sinitskii, A.S.; Eckerlebe, H.

    2009-01-01

    The structural and magnetic properties of nickel inverse opal photonic crystal have been studied by complementary experimental techniques, including scanning electron microscopy, wide-angle and small-angle diffraction of synchrotron radiation, and polarized neutrons. The sample was fabricated by ele

  5. Atomic structure of glassy Mg60Cu30Y10 investigated with EXAFS, x-ray and neutron diffraction, and reverse Monte Carlo simulations

    DEFF Research Database (Denmark)

    Jovari, P.; Saksl, K.; Pryds, Nini;

    2007-01-01

    Short range order of amorphous Mg60Cu30Y10 was investigated by x-ray and neutron diffraction, Cu and Y K-edge x-ray absorption fine structure measurements, and the reverse Monte Carlo simulation technique. We found that Mg-Mg and Mg-Cu nearest neighbor distances are very similar to values found i...

  6. High-pressure neutron diffraction on fluid carbon tetrafluoride and interpretation by reverse Monte Carlo simulations

    Science.gov (United States)

    Waldner, I.; Bassen, A.; Bertagnolli, H.; Tödheide, K.; Strauss, G.; Soper, A. K.

    1997-12-01

    Neutron scattering experiments on carbon tetrafluoride (CF4) at high pressure were performed along the 370 K isotherm at three supercritical densities, covering a density range from ρ=1.07 to 1.26 g cm-3. The structure factors of the investigated thermodynamic states and the weighted sums of the atom pair correlation functions are presented. The variation of the density has only a weak effect on the structure factors. The experimentally obtained total atom pair correlation functions are interpreted with reverse Monte Carlo simulations. The atom pair correlation functions and angular distribution functions indicate a completely disordered arrangement of the molecules in fluid CF4 with no significant short-range orientational order, except for very close distances.

  7. Isotope effects in water as investigated by neutron diffraction and path integral molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Zeidler, Anita [University of Bath; Salmon, Phil [University of Bath; Fischer, Henry E [Institut Laue-Langevin (ILL); Neuefeind, Joerg C [ORNL; Simonson, J Michael {Mike} [ORNL; Markland, Thomas [Columbia University

    2012-01-01

    The structure of heavy and light water at 300 K was investigated by using a joint approach in which the method of neutron di raction with oxygen isotope substitution was combined with path integral molecular dynamics simulations. The di raction results, which give intra-molecular O-D and O-H bond distances of 0.985(5) and 0.990(5) A, were found to be in best agreement with those obtained by using the exible anharmonic TTM3-F water model. Both techniques show a di erence of '0.5% between the O-D and O-H intra-molecular bond lengths and the results support a competing quantum e ects model for water in which its structural and dynamical properties are governed by an o set between intra-molecular and inter-molecular quantum contributions. Further consideration of the O-O correlations is needed in order to improve agreement with experiment.

  8. In situ shape and distance measurements in neutron scattering and diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Satoru; Mendelson, R.A. [Univ. of California, San Francisco, CA (United States)

    1994-12-31

    Neutron scattering combined with selective isotopic labeling and contrast matching is useful for obtaining in situ structural information about a selected particle, or particles, in a macromolecular complex. The observed intensities, however, may be distorted by inter-complex interference and by scattering-length-density fluctuations of the (otherwise) contrast-matched portions. Methods have been proposed to cancel out such distortions (Hoppe`s method, the Statistical Labeling Method, and the Triple Isotopic Substitution Method). With these methods as well as related unmixed-sample methods, structural information about the selected particles can be obtained without these distortions. We have generalized these methods so that, in addition to globular particles in solution, they can be applied to in situ structures of systems having underlying symmetry and/or net orientation as well. The information obtainable from such experiments is discussed.

  9. Test experiment to search for a neutron EDM by the Laue diffraction method

    CERN Document Server

    Fedorov, V V; Lelievre-Berna, E; Nesvizhevsky, V V; Petoukhov, A; Semenikhin, S Y; Soldner, T; Tasset, F; Voronin, V V

    2005-01-01

    A prototype experiment to measure the neutron electric dipole moment (nEDM) by spin-rotation in a non-centrosymmetric crystal in Laue geometry was carried out in order to investigate the statistical sensitivity and systematic effects of the method. The statistical sensitivity to the nEDM was about $6\\cdot 10^{-24}$ e$\\cdot $cm per day and can be improved by one order of magnitude for the full scale setup. Systematics was limited by the homogeneity of the magnetic field in the crystal region and by a new kind of spin rotation effect. We attribute this effect to a difference of the two Bloch waves amplitudes in the crystal, which is caused by the presence of a small crystal deformation due to a temperature gradient. In a revised scheme of the experiment, this effect could be exploited for a purposeful manipulation of the Bloch waves.

  10. Neutron Diffraction Studies of Some Rare Earth-Transition Metal Deuterides.

    Science.gov (United States)

    1984-04-01

    in the x 0.4 to 0.6 range resulting in an absence of long range-maqntic order. The phenomenon is srir2o that expected of spin-glass behavior.- eutron ...diffraction and thermal magnetization measurements on small single crystals of ErNi3, ErCo3, and ErFe 3 (space group R3m) show that the...Sparallel to b ........................... 37 13. Thermal variations of the spontaneous moment components Hs1< and along C and -b

  11. Development and characterization of electron sources for diffraction applications

    Energy Technology Data Exchange (ETDEWEB)

    Casandruc, Albert

    2015-12-15

    The dream to control chemical reactions that are essential to life is now closer than ever to gratify. Recent scientific progress has made it possible to investigate phenomena and processes which deploy at the angstroms scale and at rates on the order femtoseconds. Techniques such as Ultrafast Electron Diffraction (UED) are currently able to reveal the spatial atomic configuration of systems with unit cell sizes on the order of a few nanometers with about 100 femtosecond temporal resolution. Still, major advances are needed for structural interrogation of biological systems like protein crystals, which have unit cell sizes of 10 nanometers or larger, and sample sizes of less than one micrometer. For such samples, the performance of these electron-based techniques is now limited by the quality, in particular the brightness, of the electron source. The current Ph.D. work represents a contribution towards the development and the characterization of electron sources which are essential to static and time-resolved electron diffraction techniques. The focus was on electron source fabrication and electron beam characterization measurements, using the solenoid and the aperture scan techniques, but also on the development and maintenance of the relevant experimental setups. As a result, new experimental facilities are now available in the group and, at the same time, novel concepts for generating electron beams for electron diffraction applications have been developed. In terms of existing electron sources, the capability to trigger and detect field emission from single double-gated field emitter Mo tips was successfully proven. These sharp emitter tips promise high brightness electron beams, but for investigating individual such structures, new engineering was needed. Secondly, the influence of the surface electric field on electron beam properties has been systematically performed for flat Mo photocathodes. This study is very valuable especially for state

  12. Applications of neutron radiography for the nuclear power industry

    Energy Technology Data Exchange (ETDEWEB)

    Craft, Aaron E.; Barton, John P.

    2016-11-01

    The World Conference on Neutron Radiography (WCNR) and International Topical Meeting on Neutron Radiography (ITMNR) series have been running over 35 years. The most recent event, ITMNR-8, focused on industrial applications and was the first time this series was hosted in China. In China, more than twenty new nuclear power plants are in construction and plans have been announced to increase the nuclear capacity further by a factor of three within fifteen years. There are additional prospects in many other nations. Neutron tests were vital during previous developments of materials and components for nuclear power applications, as reported in this conference series. For example a majority of the 140 papers in the Proceedings of the First WCNR are for the benefit of the nuclear power industry. Included are reviews of the diverse techniques being applied in Europe, Japan, the United States, and at many other centers. Many of those techniques are being utilized and advanced to the present time. Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Applications include examination of nuclear waste, nuclear fuels, cladding, control elements, and other critical components. In this paper, the techniques developed and applied internationally for the nuclear power industry since the earliest years are reviewed, and the question is asked whether neutron test techniques can be of value in development of the present and future generations of nuclear power plants world-wide.

  13. Residual elastic strain measurement in heat-treated and/or plastically deformed two-phase stainless steel by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Harjo, S.; Sato, Hideo; Tomota, Yo [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering; Ono, Masayoshi

    1997-06-01

    The testing method of microscopic residual stress in commercial material using neutral diffraction is not established yet like that using x-ray diffraction. Then, in this research a microscopic residual stress of {alpha}/{gamma} two phase Fe-Cr-Ni alloy convenient for an experiment was tried by using neutron diffraction, to investigate its testing method. And further, a test using x-ray diffraction was also conducted for their comparison. As a result, some problems in the residual stress measurement using neutron diffraction were summarized shown as follows. On precision of d{sub 0}, since proper reference material was difficult for material M to provide, a preferable result could not be obtained in the stress measurement using PSD method. On curve fitting, by changing from a multi order function to a Voigt function by using the curve-fitting method, it was found that the peak could be fit better. Furthermore, on the problem of testing condition, because of weak intensity of the neutron source, it was necessary to use a monochromator capable of collecting incident beam like Bent crystal, and to improve sample setting, counter and slit. (G.K.)

  14. APPLICATION OF NOVEL NEUTRON CORRELATION TECHNIQUES TO NUCLEAR MATERIAL MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Sale, K

    2006-06-09

    Confirmation of the fissile mass of a system containing plutonium can be done using neutron multiplicity techniques. This can be accomplished with a detector system that is smaller and less costly than a standard neutron multiplicity counter (NMC). Also the fissile mass of a uranium containing system can be confirmed by passive means. Recent work at Lawrence Livermore National Laboratory has demonstrated that simple slab neutron detectors and a novel approach to data acquisition and analysis can be used to make an accurate measurement of the mass of fissile materials. Purely passive measurement of kilogram quantities of highly enriched uranium (HEU) have also been shown to be feasible. In this paper we discuss calculational tools for assessing the application of these techniques to fissile material transparency regimes. The tools required to adequately model the correlations and their application will be discussed.

  15. The structure of para-toluidine by X-ray and neutron diffraction; Etude de la structure de la para-toluidine par la diffraction des rayons X et des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bertinotti, A.L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [French] La structure cristalline et moleculaire de la para-toluidine a ete resolue a l'aide de la diffraction des rayons X et des neutrons. L'analyse a revele que la structure presentait un encha ement particulier des molecules, liees entre elles par des ponts hydrogene. La presence des liaisons rend compte de l'elevation du point de fusion de la para-toluidine par rapport a celui des carbures benzeniques de symetrie et de poids moleculaires voisins. La direction des liaisons explique le clivage facile (001) des cristaux obtenus par fusion et l'anisotropie de croissance des cristaux en phase vapeur. Une methode de recherche de structures par ordinateur a ete elaboree, faisant usage du concept d'energie reticulaire applique aux molecules considerees comme rigides et faisant appel a une methode de simplexe pour la minimisation des fonctions sans calcul de derivees. La maniere dont est exploitee l'information disponible permet d'accro re, comme cela est montre dans le cas de la para-toluidine, l'etendue du domaine de

  16. Neutrons and synchrotron radiation in engineering materials science from fundamentals to applications

    CERN Document Server

    Schreyer, Andreas; Clemens, Helmut; Mayer, Svea

    2017-01-01

    Retaining its proven concept, the second edition of this ready reference specifically addresses the need of materials engineers for reliable, detailed information on modern material characterization methods. As such, it provides a systematic overview of the increasingly important field of characterization of engineering materials with the help of neutrons and synchrotron radiation. The first part introduces readers to the fundamentals of structure-property relationships in materials and the radiation sources suitable for materials characterization. The second part then focuses on such characterization techniques as diffraction and scattering methods, as well as direct imaging and tomography. The third part presents new and emerging methods of materials characterization in the field of 3D characterization techniques like three-dimensional X-ray diffraction microscopy. The fourth and final part is a collection of examples that demonstrate the application of the methods introduced in the first parts to probl...

  17. Laue diffraction: The key to neutron crystallography from submillimetric-volume single crystals

    Science.gov (United States)

    Lemée-Cailleau, M.-H.; McIntyre, G. J.; Wilkinson, C.

    2005-12-01

    For several decades, chemists and physicists have been fascinated by molecular compounds rich in delocalized electrons. In the solid state these compounds may offer a very rich fan of properties: optical, conduction and dielectric, magneticldots Each state is the result of a delicate balance amongst intra- and/or intermolecular interactions which can be controlled, not just by direct chemical substitution, but also by external parameters such as temperature, pressure, continuous electric or magnetic fields, or by light. The recent evolution of this field of science towards more and more sophisticated materials makes also more and more difficult their crystal growth. While neutron scattering is an extremely powerful technique to get precise structural information, it is also often disregarded in this field because usually large single crystals are required. With the recent renaissance of Laue techniques using the very intense flux provided by the reactor of the Institut Laue-Langevin (ILL), accurate structural and/or magnetic information can be now extracted routinely from molecular crystals of volume 0.1 mm3 or smaller, with easy possibilities of high pressure (up to 3 GPa) down to 0.2 K. A general survey of these new possibilities is illustrated by an example taken from the field of low-dimensional organic complexes.

  18. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    Science.gov (United States)

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  19. Non-destructive magneto-strain analysis of YB2Cu3Oy superconducting magnets using neutron diffraction in the time-of-flight mode

    Science.gov (United States)

    Tomita, M.; Muralidhar, M.; Suzuki, K.; Ishihara, A.; Fukumoto, Y.; Osamura, K.; Machiya, S.; Harjo, S.

    2012-09-01

    In general, neutron diffraction allows a non-destructive investigation of bulk samples. In this study, a magneto-strain analysis of the trapped field in YB2Cu3Oy "YBCO" superconducting bulks was carried out at 45 K using neutron diffraction time-of-flight (TOF) method. The TAKUMI TOF neutron diffractometer offers unique advantages, including accommodation of large objectives, control of the experimental set-up using a 4-axial goniometer (XYZθ), and a positional resolution of 0.01 mm allowing an accurate sample positioning. As a result, the lattice strain in the YB2Cu3Oy material could be estimated in both radial and hoop directions by estimating the difference of plane spacing with/without the trapped magnetic field. The results indicate that the samples with a low trapped field values have smaller magnetic strain than those with a high trapped field. Further, the strain in the hoop direction is higher than that in the radial direction. The present results indicate that neutron diffraction measurements are an effective method for evaluating the bulk residual strains in a non-destructive manner.

  20. Deuterated polyethylene coatings for ultra-cold neutron applications

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, Th.; Geltenbort, P. [Institut Laue-Langevin, 38042 Grenoble Cedex 9 (France); Fierlinger, P.; Gutsmiedl, E.; Hollering, A.; Petzoldt, G.; Ruhstorfer, D.; Stuiber, St.; Taubenheim, B.; Windmayer, D. [Physikdepartment, Technische Universität München, D-85748 Garching (Germany); Lauer, T.; Schroffenegger, J.; Zechlau, T. [Forschungsneutronenquelle Heinz Maier-Leibnitz, Technische Universität München, D-85748 Garching (Germany); Seemann, K. M. [Physik-Department E21 & Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85747 Garching (Germany); Soltwedel, O. [Max-Planck-Institute for Solid State Research, Outstation at MLZ, Lichtenbergstr. 1, 85747 Garching (Germany)

    2015-09-21

    We report on the fabrication and use of deuterated polyethylene as a coating material for ultra-cold neutron (UCN) storage and transport. The Fermi potential has been determined to be 214 neV, and the wall loss coefficient η is 1.3 × 10{sup 4} per wall collision. The coating technique allows for a wide range of applications in this field of physics. In particular, flexible and quasi-massless UCN guides with slit-less shutters and seamless UCN storage volumes become possible. These properties enable the use in next-generation measurements of the electric dipole moment of the neutron.

  1. Magnetic structure of La2O3FeMnSe2: neutron diffraction and physical property measurements.

    Science.gov (United States)

    Landsgesell, S; Blumenröther, E; Prokeš, K

    2013-02-27

    We report on the characterization of the mixed layered lanthanum iron manganese oxyselenide La(2)O(3)FeMnSe(2), where Fe and Mn share the same crystallographic position. The susceptibility data show a magnetic transition temperature of 76 K and a strong difference between field cooled and zero field cooled (ZFC) data at low fields. While the ZFC magnetization curve exhibits negative values below about 45 K, hysteresis measurement reveals, after an initial negative magnetic moment, a hysteresis loop typical for ferromagnetic material, pointing to competing ferromagnetic and antiferromagnetic interactions. Resistivity and dielectric permittivity measurements indicate that La(2)O(3)FeMnSe(2) is a semiconductor. We performed x-ray diffraction at 295 K and neutron diffraction at 90 and 1.7 K. The nuclear and magnetic structure was refined in the space group I4/mmm with a = 4.11031 (3) Å and c = 18.7613 (2) Å at 295 K. We did not detect a structural distortion and the Fe and Mn atoms were randomly distributed. The magnetic order was found to be antiferromagnetic, with a propagation vector q = (0,0,0) and magnetic moments of 3.44 (5) μ(B) per Fe/Mn atom aligned within the a-b plane. This magnetic order is different with respect to the pure Fe or Mn compositions reported in other studies.

  2. Neutron Diffraction Study of Pyrochlore Compound R 2Ru 2O 7 (R=Y, Nd) above and below the Spin Freezing Temperature

    Science.gov (United States)

    Ito, Masafumi; Yasui, Yukio; Kanada, Masaki; Harashina, Hiroshi; Yoshii, Shunsuke; Murata, Kazuhiro; Sato, Masatoshi; Okumura, Hajime; Kakurai, Kazuhisa

    2000-03-01

    Neutron Rietveld analyses have been carried out onY2Ru2O7 and Nd2Ru2O7 to clarify theprimary mechanism of the transition at T G to the spin-glass-likestate which is accompanied by the specific heat jump. The resultsindicate that the lattice system does not seem to participate in thetransition and changes of the neutron diffraction data with decreasingtemperature through T G can consistently be understood by theordering of magnetic moments at Ru sites to an almost long rangeordered state, even though the low temperature phase is glassy in themacroscopic sense.

  3. Analyze of phase's mechanical behaviour of a multiphase polycrystalline alloy by X-ray and neutron diffraction; Analyse du comportement mecanique des constituants d'un alliage polycristallin multiphase par diffraction des rayons X et neutronique

    Energy Technology Data Exchange (ETDEWEB)

    Dakhlaoui, R

    2006-12-15

    The aim of this work is to propose a methodology using diffraction methods and theoretical approaches of self-consistent modeling in order to analyze and better understand the mechanical behavior of each phase of hot-rolled duplex stainless steel. The purpose of the experimental study is to characterize the local mechanical behavior of phases under uniaxial loading. X-ray and neutron diffraction which enable to measure strains in each phase separately were used in this aim. Austenitic and ferritic phase stresses are determined by X-ray diffraction during tensile tests. Evolution of the elastic strains in each phase was measured by neutron diffraction using 'time-of-flight' method during tensile and compression tests. Elastic constants were given using the self-consistent model for a purely elastic deformation. To reproduce the mechanical behaviour of the studied material, self-consistent polycrystalline micro-mechanical model for elastoplastic deformation has been adapted and confronted to experimental results. Crystallographic texture and initial residual stresses were considered in this analysis. Critical shear stresses and hardening parameters of each phase of the studied duplex steel have been identified. Results of this study showed that the austenitic phase represents the softest and the most hardenable phase. Taking into account in calculations the initial residual stresses in the non deformed sample leads to the conclusion that the initial stresses modify considerably the values of phase's yield stresses. Good agreement has been noted comparing results obtained by XRD to those obtained by neutron diffraction. The problem of relaxation of normal stresses in the analysed layer by X-rays was analysed and discussed. Using XRD and self-consistent modelling, the effect of the chemical composition of the duplex stainless steel and the influence of ageing at 400 C degrees for 1000 h on the mechanical behaviour of austenitic and ferritic phases have

  4. Commensurate magnetic structures of RMn2O5 (R=Y,Ho,Bi) determined by single-crystal neutron diffraction

    Science.gov (United States)

    Vecchini, C.; Chapon, L. C.; Brown, P. J.; Chatterji, T.; Park, S.; Cheong, S.-W.; Radaelli, P. G.

    2008-04-01

    Precise magnetic structures of RMn2O5 , with R=Y,Ho,Bi in the commensurate and/or ferroelectric regime, have been determined by single-crystal neutron diffraction. For each system, the integrated intensities of a large number of independent magnetic Bragg reflections have been measured, allowing unconstrained least-squares refinement of the structures. The analysis confirms the previously reported magnetic configuration in the ab plane, in particular, the existence of zigzag antiferromagnetic chains. For the Y and Ho compounds, additional weak magnetic components parallel to the c axis were detected, which are modulated in phase quadrature with the a-b components. This component is extremely small in the BiMn2O5 sample, therefore supporting symmetric exchange as the principal mechanism inducing ferroelectricity. For HoMn2O5 , a magnetic ordering of the Ho moments was observed, which is consistent with a superexchange interaction through the oxygens. For all three compounds, the point symmetry in the magnetically ordered state is m2m , allowing the polar b axis found experimentally.

  5. Comparison between Neutron Diffraction measurements and numerical simulation of residual stresses of a Wire-Drawing process

    Directory of Open Access Journals (Sweden)

    Tomaz Fantin de Souza

    2013-04-01

    Full Text Available In this work, a drawing processed was simulated to calculate forces and the resulting residual stresses in the material. The calculated residual stresses were compared with experimentally measured residual stresses by the Neutron Diffraction Method. The modeled process was the Wire Drawing. The necessary parameters to model the process were taken from an industrial currently used process. Rods of an AISI 1045 steel with nominal diameters of 21.46 mm were reduced to 20.25 mm by drawing with an drawing angle of 15°. Compression tests were used to determinate flow curves of the real material an used in the simulation models. The possibility to estimate drawing forces by numerical simulation was evaluated by comparing simulated results with values from empirical equations given by the literature. The results have shown a sufficient accuracy for the calculation of forces, but the comparison of residual stresses has shown differences to the experimentally determined ones that can be minimized by the consideration of high strain rates in the compression tests, anisotropy of the material and kinematic hardening.

  6. Geometrically frustrated magnetic structures of the heavy-fermion compound CePdAl studied by powder neutron diffraction

    Science.gov (United States)

    Dönni, A.; Ehlers, G.; Maletta, H.; Fischer, P.; Kitazawa, H.; Zolliker, M.

    1996-12-01

    The heavy-fermion compound CePdAl with ZrNiAl-type crystal structure (hexagonal space group 0953-8984/8/50/043/img8) was investigated by powder neutron diffraction. The triangular coordination symmetry of magnetic Ce atoms on site 3f gives rise to geometrical frustration. CePdAl orders below 0953-8984/8/50/043/img9 with an incommensurate antiferromagnetic propagation vector 0953-8984/8/50/043/img10, and a longitudinal sine-wave (LSW) modulated spin arrangement. Magnetically ordered moments at Ce(1) and Ce(3) coexist with frustrated disordered moments at Ce(2). The experimentally determined magnetic structure is in agreement with group theoretical symmetry analysis considerations, calculated by the program MODY, which confirm that for Ce(2) an ordered magnetic moment parallel to the magnetically easy c-axis is forbidden by symmetry. Further low-temperature experiments give evidence for a second magnetic phase transition in CePdAl between 0.6 and 1.3 K. Magnetic structures of CePdAl are compared with those of the isostructural compound TbNiAl, where a non-zero ordered magnetic moment for the geometrically frustrated Tb(2) atoms is allowed by symmetry.

  7. Investigation of the magnetic properties in thin Fe50Pt50-xRhx films by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, J.; Lott, D.; Schreyer, A. [GKSS Research Centre (Germany); Mankey, G.J. [University of Alabama, MINT Center (United States); Schmidt, W.; Schmalzl, K. [Juelich Research Centre (Germany); Tartakowskaya, E. [Institute for Magnetism, National Accademy of Science (United States)

    2009-07-01

    FePt-based alloys are typically the material of choice for magnetic information storage media. The high magnetic moment of Fe gives a large magnetization and the large atomic number of Pt results in a high magnetic anisotropy. This combination enables the written bits to be smaller than ever before, since magnetic grains with a high magnetic anisotropy are more thermally stable. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix, e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Bulk samples of Fe{sub 50}Pt{sub 40}Rh{sub 10} for example, studied by magnetization measurements refer to an antiferromagnetic (AF)/ferromagnetic (FM) phase transition at about 150 K when heated. Additional magnetostriction measurements indicate that the phase transition could also be induced by applying a magnetic field. Here we present results on several Fe{sub 50}Pt{sub 50-x}Rh{sub x} films. These films were examined by neutron diffraction in dependence of temperature and magnetic field. The observed magnetic behaviours differ significant from the behaviour of the bulk system.

  8. Neutron diffraction measurements for the determination of heat treatment effectiveness in generating compressive residual stress in an automotive crown gear

    Science.gov (United States)

    Albertini, G.; Bruno, G.; Fiori, F.; Girardin, E.; Giuliani, A.; Quadrini, E.; Romani, F.

    2000-03-01

    Thermal austenitizing and tempering treatments are being developed in automotive industry to prevent crack initiation and propagation, especially in components where stress intensity factors influence the stress field and ultimately the fatigue life of the component. This is the case of crown gears, where the tooth root typically undergoes impulsive and very high loads which frequently cause cracking if tensile residual stresses are present at the surface. The sign reversal of these stresses is the aim of austenitizing and tempering treatments. In this work neutron diffraction measurements of residual stress (RS) on a UNI55Cr3 steel crown gear, carried out at HMI-BENSC , are presented. The sample was submitted to a new multi-frequency induction technique whose effectiveness was checked. Comparisons with X-ray measurements are shown, and RS measured by X-rays on a similar shot-peened sample are also mentioned. Experiments at HMI-BENSC have received financial support by the European Commission under the TMR/LSF Access Programme (contract no. ERBFMGE CT950060).

  9. Refinement of atomic and magnetic structures using neutron diffraction for synthesized bulk and nano-nickel zinc gallate ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Ata-Allah, S.S. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt); Balagurov, A.M. [Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Moscow region (Russian Federation); Hashhash, A. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt); Bobrikov, I.A. [Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Moscow region (Russian Federation); Hamdy, Sh. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt)

    2016-01-15

    The parent NiFe{sub 2}O{sub 4} and Zn/Ga substituted spinel ferrite powders have been prepared by solid state reaction technique. As a typical example, the Ni{sub 0.7}Zn{sub 0.3}Fe{sub 1.5}Ga{sub 0.5}O{sub 4} sample has been prepared by sol–gel auto combustion method with the nano-scale crystallites size. X-ray and Mössbauer studies were carried out for the prepared samples. Structure and microstructure properties were investigated using the time-of-flight HRFD instrument at the IBR-2 pulsed reactor, at a temperatures range 15–473 K. The Rietveld refinement of the neutron diffraction data revealed that all samples possess cubic symmetry corresponding to the space group Fd3m. Cations distribution show that Ni{sup 2+} is a complete inverse spinel ion, while Ga{sup 3+} equally distributed between the two A and B-sublattices. The level of microstrains in bulk samples was estimated as very small while the size of coherently scattered domains is quite large. For nano-structured sample the domain size is around 120 Å.

  10. Neutron diffraction residual stress analysis of Al{sub 2}O{sub 3}/Y-TZP ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Fan, K.; Ruiz-Hervias, J.; Gurauskis, J.; Sanchez-Herencia, A. J.; Baudin, C.

    2016-05-01

    Residual stress measurements were conducted by time-of-flight neutron diffraction and Rietveld analysis method in Al{sub 2}O{sub 3}/Y-TZP ceramic composites fabricated by different green processing techniques (a novel tape casting and conventional slip casting) and with different Y-TZP content (5 and 40 vol.% Y-TZP). The results show that the residual stresses in Y-TZP particulates are tensile and the ones in Al{sub 2}O{sub 3} matrix are compressive, with almost flat through-thickness residual stress profiles in all bulk samples. As Y-TZP content increased, tension in Y-TZP phase was decreased but compression in Al{sub 2}O{sub 3} matrix was increased (in absolute value). The values of residual stresses for both phases were mainly dependent on the Y-TZP content in the studied Al{sub 2}O{sub 3}/Y-TZP composites, irrespective of sample orientation and fabrication processes (a novel tape casting and conventional slip casting). (Author)

  11. Network structure of molybdate glasses by neutron and X-ray diffraction and reverse Monte Carlo modelling

    Science.gov (United States)

    Fabian, M.; Svab, E.; Krezhov, K.

    2016-09-01

    Rare-earth molybdate glasses have been prepared by rapid quench technique, the network structure was investigated by neutron and high-energy X-ray diffraction. For data evaluation the reverse Monte Carlo simulation technique was applied to obtain a possible 3dimensional network configuration, which is consistent with the experimental data. From the modelling the partial atomic correlation functions giJ(r) and the coordination number distributions CNij have been revealed. Formation of MoO4 (55%) and MoO6 (25%) units was established for the binary 90MoO3-10Nd2O3 glass. The B-O first neighbour distribution show a relatively broad first neighbour distance at 1.40A, the average coordination numbers show the presents of trigonal BO3 and tetrahedral BO4 groups. For 50MoO3-25Nd2O3-25B2O3 sample mixed MoO4-BO4 and MoO4-BO3 linkages form pronounced intermediate-range order.

  12. Molecular Visualization of Methane - Carbon Dioxide Solid Solution in Gas Hydrates by High Resolution Neutron Powder Diffraction

    Science.gov (United States)

    Everett, M.; Rawn, C.; Huq, A.; Chakoumakos, B. C.; Phelps, T. J.

    2012-12-01

    The exchange of CO2 for CH4 in natural gas hydrates could produce energy from untapped sources while at the same time sequestering CO2. In addition to the energy and environmental aspects the solid solution of (CH4)1-x(CO2)x 5.75H2O provides a framework inclusion structure that enables the scientific study of how two molecules that differ greatly in their bonding, shape, coordination and molecular weight can influence the structure and properties of the compound and interact with the framework that occludes the molecules. Samples synthesized by cooling liquid water pressurized with either pure CH4 or CO2 or mixtures of the two gases to temperatures where hydrate formation occurs have been studied using high-resolution neutron diffraction. Static images of the nuclear scattering density of the free moving gas molecules have been determined. Cage occupants and occupancies, the volume change of the unit cell and the individual cages based on composition have been determined.

  13. Inhomogeneity and relaxation phenomena in the graphite anode of a lithium-ion battery probed by in situ neutron diffraction

    Science.gov (United States)

    Zinth, Veronika; von Lüders, Christian; Wilhelm, Jörn; Erhard, Simon V.; Hofmann, Michael; Seidlmayer, Stefan; Rebelo-Kornmeier, Joana; Gan, Weimin; Jossen, Andreas; Gilles, Ralph

    2017-09-01

    In this study, lithium gradients forming in the graphite anode of a commercial 18650-type lithium-ion battery during discharge and the associated relaxation processes after discharge were monitored by neutron diffraction. The experiments reveal the coexistence of several Li1-xC6 phases with different lithium contents during discharge, which can be explained by the formation of an inhomogeneity or lithium gradient in the graphite anode. The observed inhomogeneity is more pronounced at higher discharging rates, but at low temperatures it appears at a rate as low as C/10. After discharge, the inhomogeneity gradually disappears and the coexisting phases diminish in favor of one or several Li1-xC6 phases with close to mean lithium content. At room temperature these relaxation processes take 20-40 min with the main changes in the first 10 min. In contrast, at -20 °C changes are still observed after 11 h. The observed phenomena can be explained by a faster delithiation of the graphite particles than the equilibration of the resulting lithium gradient by lithium diffusion in the solid phase during discharge.

  14. Ferromagnetic Cu-O-Cu coupling in CaCu3Sn4O12 probed by neutron diffraction.

    Science.gov (United States)

    Kayser, P; Retuerto, M; Sánchez-Benítez, J; Martínez-Lope, M J; Fernández-Díaz, M T; Alonso, J A

    2012-12-12

    The A-site ordered perovskite oxide with the formula CaCu(3)Sn(4)O(12) has been synthesized in polycrystalline form under moderate pressure conditions (3.5 GPa) in combination with high temperature (1000 °C). This oxide crystallizes in the cubic space group [Formula: see text] (no. 204) with the unit-cell parameter a = 7.64535(6) Å at 300 K. The SnO(6) network is extremely tilted, giving rise to a square planar coordination for Cu(2+) cations. The non-magnetic character of Sn(4+) offers an excellent opportunity to probe the magnetism of Cu(2+) at the A sublattice in CaCu(3)Sn(4)O(12). Magnetic susceptibility shows that this compound is ferromagnetic below T(C) = 10 K, which is an unusual magnetic behaviour in cuprates. This peculiar aspect has been examined by neutron powder diffraction. The refinement of the magnetic structure at 4 K indeed indicates a parallel coupling between Cu(2+) spins with a magnetic moment of 0.5 μ(B)/Cu atom.

  15. Collinear antiferromagnetism in trigonal SrMn2As2 revealed by single-crystal neutron diffraction

    Science.gov (United States)

    Das, Pinaki; Sangeetha, N. S.; Pandey, Abhishek; Benson, Zackery A.; Heitmann, T. W.; Johnston, D. C.; Goldman, A. I.; Kreyssig, A.

    2017-01-01

    Iron pnictides and related materials have been a topic of intense research for understanding the complex interplay between magnetism and superconductivity. Here we report on the magnetic structure of SrMn2As2 that crystallizes in a trigonal structure (P\\bar{3}m1 ) and undergoes an antiferromagnetic (AFM) transition at {{T}\\text{N}}=118(2) K. The magnetic susceptibility remains nearly constant at temperatures T≤slant {{T}\\text{N}} with \\boldsymbol{H}\\parallel \\boldsymbol{c} whereas it decreases significantly with \\boldsymbol{H}\\parallel \\boldsymbol{a}\\boldsymbol{b} . This shows that the ordered Mn moments lie in the \\boldsymbol{a}\\boldsymbol{b} plane instead of aligning along the \\boldsymbol{c} -axis as in tetragonal BaMn2As2. Single-crystal neutron diffraction measurements on SrMn2As2 demonstrate that the Mn moments are ordered in a collinear Néel AFM phase with {{180}\\circ} AFM alignment between a moment and all nearest neighbor moments in the basal plane and also perpendicular to it. Moreover, quasi-two-dimensional AFM order is manifested in SrMn2As2 as evident from the temperature dependence of the order parameter.

  16. DMSO-Induced Dehydration of DPPC Membranes Studied by X-ray Diffraction, Small-Angle Neutron Scattering, and Calorimetry

    CERN Document Server

    Kiselev, M A; Kisselev, A M; Grabielle-Madelmond, C; Ollivon, M

    1999-01-01

    The influence of dimethyl sulfoxide (DMSO) on membrane thickness, multilamellar repeat distance, and phase transitions of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) was investigated by X-ray diffraction and small-angle neutron scattering (SANS). The differential scanning calorimetry (DSC) study of water freezing and ice melting was performed in the ternary DPPC /DMSO /water and binary DMSO /water systems. The methods applied demonstrated the differences in membrane structure in three sub-regions of the DMSO mole fraction (X_dmso): from 0.0 to 0.3 for the first, from 0.3 to 0.8 for the second, and from 0.9 to 1.0 for the third sub-region. The thickness of the intermembrane solvent at T =20C decreases from 14.4 +/- 1.8 A at X_dmso =0.0 to 7.8 +/- 1.8 A at X_dmso =0.1. The data were used to determine the number of free water molecules in the intermembrane space in the presence of DMSO. The results for 0.0 < X_dmso < 0.3 were explained in the framework of DMSO-induced dehydration of the interme...

  17. Simultaneous structural and magnetic transitions in YFe 4Ge 2 studied by neutron diffraction and magnetic measurements

    Science.gov (United States)

    Schobinger-Papamantellos, P.; Rodríguez-Carvajal, J.; André, G.; Duong, N. P.; Buschow, K. H. J.; Tolédano, P.

    2001-10-01

    The magnetic behaviour of the tetragonal YFe 4Ge 2 compound has been studied by neutron diffraction and bulk magnetisation measurements. Magnetic ordering occurs below T N=43.5 K simultaneously with a structural transition from tetragonal P4 2/mnm→Pnnm to orthorhombic symmetry. Both transitions are of first order. The symmetry breaking is connected with primary displacive order parameters involving shifts of the Fe atoms. The Fe site splits into two sites in Pnnm, the shifts of the Fe atoms with respect to the tetragonal phase have opposite signs along the a (dilatation) and b (contraction) axes. This induces the symmetry breaking tensile strains. The planar canted antiferromagnetic arrangement with eight sublattices is the ground state associated with a magnetic energy involving isotropic exchange and anisotropic (relativistic) interactions. The magnetic structure is invariant under the magnetic space group P{2 1}/{n' } {2 1}/{n' } {2 1}/{m' } ( Sh58399) . The moments of the two orbits have the same value. At 1.5 K the Fe moment equals 0.63(4) μB/Fe atom. The YFe 4Ge 2 magnetostructural phenomena are compared to the more complex analogue of the ErFe 4Ge 2 compound. The structural and magnetic transitions are described phenomenologically within a Landau-Dzialoshinski approach which assumes a triggering mechanism, in which the spontaneous strain is triggered by the exchange contribution to the magnetic ordering.

  18. Neutron diffraction study of multiferroic Mo-doped CoFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dwivedi, G.D. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumari, Poonam [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Shahi, P. [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Yang, H.D. [Department of Physics, National Sun Yat-Sen University, Kahosiung 80424, Taiwan (China); Ghosh, A.K. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Chatterjee, Sandip, E-mail: schatterji.app@iitbhu.ac.in [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-04-01

    Neutron diffraction measurements have been carried out to study the coexistence of magnetic ordering and ferroelectricity at room temperature in CoFe{sub 1.8}Mo{sub 0.2}O{sub 4}. It is observed from this study that the Mo{sup 6+} preferentially occupies the octahedral site and it converts some of the Fe{sup 3+} ions into Fe{sup 2+} ions in the tetrahedral site. The conversion of Fe{sup 3+} ions into Fe{sup 2+} ions modulate the Fe–Fe distances which in effect induce the ferroelectricity in magnetically ordered CoFe{sub 1.8}Mo{sub 0.2}O{sub 4}. - Highlights: • CoFe{sub 2}O{sub 4} is an inverse spinel with ferromagnetic ordering. • Mo{sup +6} ion is doped in Fe site to induce ferroelectricity. • Mo{sup 6+} occupies the Octahedral site and it converts some of the Fe{sup 3+} ions into Fe{sup 2+} ions. • The conversion of Fe{sup 3+} ions into Fe{sup 2+} ions modulate the Fe–Fe distances which in effect induce the ferroelectricity in CoFe{sub 2}O{sub 4}.

  19. In-situ neutron diffraction study of cathode/electrolyte interactions under electrical load and elevated temperature

    Science.gov (United States)

    Tonus, F.; Skinner, S. J.

    2016-05-01

    Fuel cells are proposed as a future energy conversion technology that will reduce greenhouse gas emissions at the point of operation due to their ability to produce electrical energy from non-hydrocarbon fuel sources. The Solid Oxide Fuel Cell (SOFC) is amongst the most efficient fuel cell types, however, due to the high cell operating temperature cation diffusion occurs between the different components of the cell, resulting in rapid degradation of the power output. In this paper we investigate cation migration between the promising intermediate temperature-SOFC cathode La1-xSrxCo1-yFeyO3-δ (LSCF) and a fluorite type electrolyte Ce1-xPrxO2-δ (CPO). The crystallographic structure evolution and degradation of the materials were studied by neutron diffraction in-situ under pseudo-operating conditions, i.e. at 600 °C under air and under electrical polarisation. The lattice parameter and cation occupancy evolution were analysed by Rietveld refinement as a function of time and applied potential. The materials were found to be stable, as no impurity formation, lattice parameter or site occupancy evolution was observed during the experiment. However La migration prior to the experiment from LSCF to CPO was observed as well as B-site vacancies in LSCF.

  20. The crystal structure of superconducting FeSe{sub 1-x}Te{sub x} by pulsed neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, M C; Llobet, A; Horigane, K; Louca, D, E-mail: mcl4v@virginia.edu

    2010-11-01

    A transition to a superconducting state was recently observed in the binary alloy of FeSe{sub 1-x}Te{sub x} system where TC rises with increasing x. The substitution of the larger Te for Se ion results in no additional charges but increases the internal chemical pressure. Earlier studies suggested that the crystal structure maintains the tetragonal P4/nmm symmetry with the substitution of Te where the average bond angle, {alpha}, decreases considerably from {approx} 104{sup 0} in FeSe to 100.5{sup 0} in the mixed phase of FeSe{sub 0.5}Te{sub 0.5}. With the use of pulsed neutron power diffraction and the Rietveld analysis, the crystal structure refinement for FeSe{sub 0.5}Te{sub 0.5} yielded very large thermal factors in the superconducting phase indicative of the presence of structural distortions that may be significant in understanding the electronic and magnetic properties of this system.

  1. Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

    Science.gov (United States)

    Smith, L.; Murphy, J. W.; Kim, J.; Rozhdestvenskyy, S.; Mejia, I.; Park, H.; Allee, D. R.; Quevedo-Lopez, M.; Gnade, B.

    2016-12-01

    Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10-6 gamma-ray efficiency.

  2. Empirically testing vaterite structural models using neutron diffraction and thermal analysis

    OpenAIRE

    Chakoumakos, Bryan C.; Pracheil, Brenda M.; Ryan P. Koenigs; Ronald M. Bruch; Mikhail Feygenson

    2016-01-01

    Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite—a metastable polymorph of CaCO3. Vaterite is an important material ranging from biomedical to personal care applications although its crystal structure is highly debated. We characterize...

  3. Application of optical diffraction method in designing phase plates

    Science.gov (United States)

    Lei, Ze-Min; Sun, Xiao-Yan; Lv, Feng-Nian; Zhang, Zhen; Lu, Xing-Qiang

    2016-11-01

    Continuous phase plate (CPP), which has a function of beam shaping in laser systems, is one kind of important diffractive optics. Based on the Fourier transform of the Gerchberg-Saxton (G-S) algorithm for designing CPP, we proposed an optical diffraction method according to the real system conditions. A thin lens can complete the Fourier transform of the input signal and the inverse propagation of light can be implemented in a program. Using both of the two functions can realize the iteration process to calculate the near-field distribution of light and the far-field repeatedly, which is similar to the G-S algorithm. The results show that using the optical diffraction method can design a CPP for a complicated laser system, and make the CPP have abilities of beam shaping and phase compensation for the phase aberration of the system. The method can improve the adaptation of the phase plate in systems with phase aberrations.

  4. Neutron diffraction study of LnBaCuFeO5+#delta#, (Ln=Y,Pr)

    DEFF Research Database (Denmark)

    Ruiz-Aragón, M.J.; Amador, U.; Morán, E.;

    1994-01-01

    Neutron diffraction studies of the title materials have been performed at 600K, R.T. and 8K. Copper and iron ions are randomly distributed in two equivalent MO2 planes being the symmetry P4/mmm for all the samples and temperatures. Some extra oxygen has been found in PrBaCuFeO5+δ destroying the AF...... ordering, present at R. T. in YBaCuFeO5. Besides this, at low temperature a magnetic phase transition has been found. On the other hand, both materials show a complex micro-structure as determined by electron diffraction....

  5. In situ neutron powder diffraction using custom-made lithium-ion batteries.

    Science.gov (United States)

    Brant, William R; Schmid, Siegbert; Du, Guodong; Brand, Helen E A; Pang, Wei Kong; Peterson, Vanessa K; Guo, Zaiping; Sharma, Neeraj

    2014-11-10

    Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles. However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications. This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries. We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the 'roll-over' cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

  6. Mechanisms of network collapse in GeO2 glass: high-pressure neutron diffraction with isotope substitution as arbitrator of competing models

    Science.gov (United States)

    Wezka, Kamil; Salmon, Philip S.; Zeidler, Anita; Whittaker, Dean A. J.; Drewitt, James W. E.; Klotz, Stefan; Fischer, Henry E.; Marrocchelli, Dario

    2012-12-01

    The structure of the network forming glass GeO2 is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only with molecular dynamics simulations made using interaction potentials that include dipole-polarization effects. When the reduced density ρ/ρ0 ≳ 1.16, where ρ0 is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO5 units versus octahedral GeO6 units as they replace tetrahedral GeO4 units. This replacement necessitates the formation of threefold coordinated oxygen atoms and leads to an increase with density in the number of small rings, where a preference is shown for sixfold rings when ρ/ρ0 = 1 and fourfold rings when ρ/ρ0 = 1.64.

  7. Applications of Neutron Bubble Dosimeters for Neutron Dose Monitoring in Mixed n-γ Fields

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Bubble dosimeter is a promising technology in the field of neutron dosimetry. It provides real-time monitoring of neutron dose, stable energy response over wide range of neutron energy, and a very low

  8. Structural analysis of PrBaMn2O5+δ under SOFC anode conditions by in-situ neutron powder diffraction

    Science.gov (United States)

    Tomkiewicz, Alex C.; Tamimi, Mazin A.; Huq, Ashfia; McIntosh, Steven

    2016-10-01

    The crystal structure and oxygen stoichiometry of the proposed double perovskite solid oxide fuel cell (SOFC) anode material PrBaMn2O5+δ were determined under SOFC anode conditions via in-situ neutron diffraction. Measurements were performed in reducing atmospheres between 692 K and 984 K. The structure was fit to a tetragonal (space group P4/mmm) layered double perovskite structure with alternating Pr and Ba A-site cation layers. Under all conditions examined, the oxygen sites in the Ba and Mn layers were fully occupied, while the sites in the Pr layer were close to completely vacant. The results of the neutron diffraction experiments are compared to previous thermogravimetric analysis experiments to verify the accuracy of both experiments. PrBaMn2O5+δ was shown to be stable over a wide range of reducing atmospheres similar to anode operating conditions in solid oxide fuel cells without significant structural changes.

  9. A method for the monitoring of metal recrystallization based on the in-situ measurement of the elastic energy release using neutron diffraction.

    Science.gov (United States)

    Christien, F; Telling, M T F; Knight, K S; Le Gall, R

    2015-05-01

    A method is proposed for the monitoring of metal recrystallization using neutron diffraction that is based on the measurement of stored energy. Experiments were performed using deformed metal specimens heated in-situ while mounted at the sample position of the High Resolution Powder Diffractometer, HRPD (ISIS Facility), UK. Monitoring the breadth of the resulting Bragg lines during heating not only allows the time-dependence (or temperature-dependence) of the stored energy to be determined but also the recrystallized fraction. The analysis method presented here was developed using pure nickel (Ni270) specimens with different deformation levels from 0.29 to 0.94. In situ temperature ramping as well as isothermal annealing was undertaken. The method developed in this work allows accurate and quantitative monitoring of the recrystallization process. The results from neutron diffraction are satisfactorily compared to data obtained from calorimetry and hardness measurements.

  10. A method for the monitoring of metal recrystallization based on the in-situ measurement of the elastic energy release using neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Christien, F., E-mail: frederic.christien@univ-nantes.fr; Le Gall, R. [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, Rue Christian Pauc, BP 50609, 44306 Nantes Cedex 3 (France); Telling, M. T. F. [ISIS Facility, Rutherford Appleton Laboratory, Chilton OX11 0QX (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford (United Kingdom); Knight, K. S. [ISIS Facility, Rutherford Appleton Laboratory, Chilton OX11 0QX (United Kingdom); Department of Earth Sciences, The Natural History Museum, Cromwell Road, London (United Kingdom)

    2015-05-15

    A method is proposed for the monitoring of metal recrystallization using neutron diffraction that is based on the measurement of stored energy. Experiments were performed using deformed metal specimens heated in-situ while mounted at the sample position of the High Resolution Powder Diffractometer, HRPD (ISIS Facility), UK. Monitoring the breadth of the resulting Bragg lines during heating not only allows the time-dependence (or temperature-dependence) of the stored energy to be determined but also the recrystallized fraction. The analysis method presented here was developed using pure nickel (Ni270) specimens with different deformation levels from 0.29 to 0.94. In situ temperature ramping as well as isothermal annealing was undertaken. The method developed in this work allows accurate and quantitative monitoring of the recrystallization process. The results from neutron diffraction are satisfactorily compared to data obtained from calorimetry and hardness measurements.

  11. Analysis of neutron diffraction spectra acquired in situ during mechanical loading of shape memory NiTiFe at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, V.B.; Manjeri, R.M. [Advanced Materials Processing and Analysis Center (AMPAC), Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Clausen, B.; Brown, D.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Vaidyanathan, R. [Advanced Materials Processing and Analysis Center (AMPAC), Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States)], E-mail: raj@mail.ucf.edu

    2008-05-25

    The Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory was used to acquire neutron diffraction spectra in situ during mechanical loading at 216 and 237 K. The experiments were performed with the objective of following the texture, strain and phase fraction evolution in the trigonal R-phase in a Ni{sub 46.8}Ti{sub 50}Fe{sub 3.2} shape memory alloy. A methodology to quantify the textures, strains and phase fractions using the General Structure Analysis System (GSAS) for Rietveld refinement of neutron diffraction spectra, is implemented and described. Emphasis is placed on evaluating the choice of P3 and P3-bar space groups for the R-phase in the refinements and the impact of this choice on the quantitative analyses of spectra.

  12. Correction of intensities for preferred orientation in neutron-diffraction data of NiTi shape-memory alloy using the generalized spherical-harmonic description

    CERN Document Server

    Sitepu, H; Stalick, J K

    2002-01-01

    Analysis of quantitative texture (crystallographic preferred orientation, PO) in polycrystalline materials is of interest not only because the PO gives errors in quantitative phase analysis, but also because it can affect the results of structure determination from powder diffraction data. In the present study, texture characterization of the polycrystalline Ni-rich NiTi shape-memory alloy (SMA) of nominal composition 50.14 atomic percent nickel has been carried out using the BT-1 high-resolution, fixed-wavelength, 32-detector powder diffractometer at the NIST Center for Neutron Research. Data were collected along the differential scanning calorimeter (DSC) heating curve. The results obtained from Rietveld refinement with the generalized spherical harmonic (GSH) description for all neutron diffraction data sets show that the weight percentages for monoclinic and cubic phases during the phase transition are consistent with the DSC heating curve. (orig.)

  13. Neutron diffraction study of the Sr 1-xBi xF 2+x solid solution quenched from 700°C : Proposition of a clustering process

    Science.gov (United States)

    Soubeyroux, J. L.; Réau, J. M.; Wahbi, M.; Sénégas, J.; Soo, Suh Kyung

    1992-07-01

    A neutron diffraction investigation of the fluorite-type Sr 1-xBi xF 2+x (0 ⩽ x ≲ 0.50) solid solution has revealed the existence of three F' F″ and F'″ interstitial flouride ions. The anionic distribution between normal and interstitial sites has been determined as a function of x. A clustering process has been proposed in Sr 1-xBi xF 2+x on the basis of neutron diffraction results and of the composition dependence of electrical properties. It consists in a progressive transformation with increasing x of 3:2:3:0 clusters into "1:0:3:0" clusters.

  14. A neutron diffraction study from 6 to 293 K and a macroscopic-scale quantum theory of the hydrogen bonded dimers in the crystal of benzoic acid

    CERN Document Server

    Fillaux, François

    2011-01-01

    The crystal of benzoic acid is comprised of tautomeric centrosymmetric dimers linked through bistable hydrogen bonds. Statistical disorder of the bonding protons is excluded by neutron diffraction from 6 K to 293 K. In addition to diffraction data, vibrational spectra and relaxation rates measured with solid-state-NMR and quasi-elastic neutron scattering are consistent with wave-like, rather than particle-like protons. We present a macroscopic-scale quantum theory for the bonding protons represented by a periodic lattice of fermions. The adiabatic separation, the exclusion principle, and the antisymmetry postulate yield a static lattice-state immune to decoherence. According to the theory of quantum measurements, vibrational spectroscopy and relaxometry involve realizations of decoherence-free Bloch states for nonlocal symmetry species that did not exist before the measurement. The eigen states are fully determined by three temperature-independent parameters which are effectively measured: the energy differen...

  15. Neutron diffraction study of the formation of ordered antiphase domains in cubic titanium carbide TiC{sub 0.60}

    Energy Technology Data Exchange (ETDEWEB)

    Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S. [Academy of Sciences of Uzbekistan, Institute of Nuclear Physics (Uzbekistan)

    2013-05-15

    A series of superstructural reflections (described within the sp. gr. Fd3m) are found to be split into three symmetric parts in the neutron powder diffraction pattern of titanium carbide TiC{sub 0.60} annealed at a temperature of 600 Degree-Sign C. No splitting of superstructural reflections is observed in the neutron diffraction pattern of TiC{sub 0.60} annealed at relatively high temperatures (780 Degree-Sign C). This phenomenon can be explained by that fact that the ordering of carbon atoms at relatively high temperatures (780 Degree-Sign C) is accompanied by the formation of randomly oriented rather large antiphase domains (APDs) (450 A). At relatively low temperatures (600 Degree-Sign C), stacking faults arise in the arrangement of partially ordered carbon atoms. In this case, relatively small ordered APDs (290 A) are formed, along with disordered ones.

  16. High-level expression and deuteration of sperm whale myoglobin: A study of its solvent structure by X-ray and neutron diffraction methods

    Energy Technology Data Exchange (ETDEWEB)

    Shu, F. [State Univ. of New York, Stony Brook, NY (United States); Ramakrishnan, V. [Brookhaven National Laboratory, Upton, NY (United States); Schoenborn, B.P. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    Neutron diffraction has become one of the best ways to study light atoms, such as hydrogens. Hydrogen however has a negative coherent scattering factor, and a large incoherent scattering factor, while deuterium has virtually no incoherent scattering, but a large positive coherent scattering factor. Beside causing high background due to its incoherent scattering, the negative coherent scattering of hydrogen tends to cancel out the positive contribution from other atoms in a neutron density map. Therefore a fully deuterated sample will yield better diffraction data with stronger density in the hydrogen position. On this basis, a sperm whale myoglobin gene modified to include part of the A cII protein gene has been cloned into the T7 expression system. Milligram amounts of fully deuterated holo-myoglobin have been obtained and used for crystallization. The synthetic sperm whale myoglobin crystallized in P2{sub 1} space group isomorphous with the native protein crystal. A complete X-ray diffraction dataset at 1.5{Angstrom} has been collected. This X-ray dataset, and a neutron data set collected previously on a protonated carbon-monoxymyoglobin crystal have been used for solvent structure studies. Both X-ray and neutron data have shown that there are ordered hydration layers around the protein surface. Solvent shell analysis on the neutron data further has shown that the first hydration layer behaves differently around polar and apolar regions of the protein surface. Finally, the structure of per-deuterated myoglobin has been refined using all reflections to a R factor of 17%.

  17. Novel Pr-Cu magnetic phase at low temperature in PrBa2Cu3O6+x observed by neutron diffraction

    DEFF Research Database (Denmark)

    Boothroyd, A.T.; Longmore, A.; Andersen, N.H.

    1997-01-01

    We have studied by neutron diffraction the magnetic ordering in Al-free crystals of PrBa2Cu3O6+x (x = 0.35 and 0.92) that do not display the AFII Cu magnetic phase. Wt find that the Pr ordering below 20 K is accompanied by a counterrotation of the Cu antiferromagnetism on each plane of the bilaye...

  18. Neutron Diffraction Study of the Structures of Ba5CuIr3O12 and Ba16Cu3Ir10O39

    NARCIS (Netherlands)

    Blake, Graeme R.; Battle, Peter D.; Sloan, Jeremy; Vente, Jaap F.; Darriet, Jacques; Weill, François

    1999-01-01

    The crystal structures of Ba5CuIr3O12 and Ba16Cu3Ir10O39 have been determined using a combination of X-ray and neutron powder diffraction data. Considering their structures to be based on hcp stacks of Ba3O9 and Ba3CuO6 layers, Ba5CuIr3O12 has a 10-layer structure, space group P3c1 with a = 10.14055

  19. Phase quantification during pseudoelastic cycling of Cu-13.1Al-4.0Ni (wt.%) single-crystal shape memory alloys using neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kannarpady, Ganesh K. [Smart Materials and MEMS Laboratory, Department of Applied Science, University of Arkansas at Little Rock, 2801 South University, ETAS 575, Little Rock, AR 72204-1099 (United States); Bhattacharyya, Abhijit [Smart Materials and MEMS Laboratory, Department of Applied Science, University of Arkansas at Little Rock, 2801 South University, ETAS 575, Little Rock, AR 72204-1099 (United States)], E-mail: axbhattachar@ualr.edu; Wolverton, Mike [Smart Materials and MEMS Laboratory, Department of Applied Science, University of Arkansas at Little Rock, 2801 South University, ETAS 575, Little Rock, AR 72204-1099 (United States); Brown, Donald W. [Materials Science and Technology Division, Los Alamos National Laboratory, NM 87545 (United States); Vogel, Sven C. [Los Alamos Neutron Science Center, Los Alamos National Laboratory, NM 87545 (United States); Pulnev, Sergei [Department of Solid State Physics, Ioffe Physico-Technical Institute, St. Petersburg (Russian Federation)

    2008-10-15

    This paper reports on the pseudoelastic, isothermal mechanical cycling of copper-aluminium-nickel single-crystals. It was found that stress-free transformation temperatures at the end of 1000 stress cycles did not change, whereas the transformation stresses decreased by about 10%; otherwise, the overall strain of 7% imposed during a loading cycle was completely recovered at the end of 1000 cycles. Non-contact multi-video extensometry uncovered a significant spatial non-uniformity in the maximum strains attained in different sections of the wire. At the end of the 1000th cycle, the top and bottom sections demonstrated very similar maximum strains while the midsection demonstrated lower strain. Phase quantification of the midsection of the wire using neutron diffraction demonstrated an increase in the stabilization of austenite from 0% in the first cycle to about 60% in the 1000th cycle. The specific nature of the tests required by neutron diffraction also uncovered a creep-like response of the SMA. Preliminary investigation suggests that this 'pseudo-creep' is due to the motion of phase fronts during the phase transformation. Neutron diffraction has also confirmed that while the single crystallinity of the SMA is excellent at 175 deg. C, there is a spread in orientation of the cubic phase at 200 deg. C with respect to the axis of the wire that is estimated at 2.17 deg. This spread disappears/reappears on mechanical loading/unloading, but decreases permanently on cyclic loading.

  20. Preliminary neutron and ultrahigh-resolution X-ray diffraction studies of the aspartic proteinase endothiapepsin cocrystallized with a gem-diol inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Tuan, Han-Fang [Spallation Neutron Source, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831 (United States); Erskine, Peter [Laboratory for Protein Crystallography, Centre for Amyloidosis and Acute Phase Proteins, UCL Department of Medicine (Hampstead Campus), Rowland Hill Street, London NW3 2PF (United Kingdom); Langan, Paul [Bioscience Division, Mailstop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Chemistry, University of Toledo, Toledo, OH 53606 (United States); Cooper, Jon [Laboratory for Protein Crystallography, Centre for Amyloidosis and Acute Phase Proteins, UCL Department of Medicine (Hampstead Campus), Rowland Hill Street, London NW3 2PF (United Kingdom); Coates, Leighton, E-mail: coatesl@sns.gov [Spallation Neutron Source, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831 (United States); Department of Chemistry, University of Toledo, Toledo, OH 53606 (United States)

    2007-12-01

    Three data sets have been collected on endothiapepsin complexed with the gem-diol inhibitor PD-135,040: a high-resolution synchrotron X-ray data set, a room-temperature X-ray data set and a neutron diffraction data set. Until recently, it has been impossible to grow large protein crystals of endothiapepsin with any gem-diol inhibitor that are suitable for neutron diffraction. Endothiapepsin has been cocrystallized with the gem-diol inhibitor PD-135,040 in a low solvent-content (39%) unit cell, which is unprecedented for this enzyme–inhibitor complex and enables ultrahigh-resolution (1.0 Å) X-ray diffraction data to be collected. This atomic resolution X-ray data set will be used to deduce the protonation states of the catalytic aspartate residues. A room-temperature neutron data set has also been collected for joint refinement with a room-temperature X-ray data set in order to locate the H/D atoms at the active site.

  1. Influence of Al on the magnetic properties of TmCo{sub 4}Al compound, a magnetic and neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Laslo, A. [CNRS, Inst. Néel, F-38042 Grenoble (France); Univ. Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France); Babes-Bolyai University, Faculty of Physics, 400084 Cluj-Napoca (Romania); Pop, V. [Babes-Bolyai University, Faculty of Physics, 400084 Cluj-Napoca (Romania); Isnard, O. [CNRS, Inst. Néel, F-38042 Grenoble (France); Univ. Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France)

    2015-03-25

    Highlights: • The existence of a compensation temperature is found for TmCo{sub 4}Al. • The crystal structure and its thermal evolution are analysed by X-ray and neutron diffraction. • The ferrimagnetic magnetic structure of TmCo{sub 4}Al is established. • Magnetic properties are determined. • Significant coercivity is reported for TmCo{sub 4}Al. - Abstract: The structural and magnetic properties of the TmCo{sub 4}Al compound are presented as deduced from magnetic measurements, X-ray and neutron powder diffraction. The crystal structure is obtained in the light of Rietveld refinement of the neutron powder diffraction pattern. The symmetry of the CaCu{sub 5} structure is preserved and the Al atom is found to substitute the Co one exclusively on the 3g atomic position. Thermal expansion of the crystal lattice is reported, the temperature variation occurring mostly along the basal hexagonal plane. This compound exhibits a ferrimagnetic structure, the Tm and Co magnetic moments being coupled antiparallel. An ordering temperature of 511 K is found. The thermal dependence of the Tm magnetic moment is obtained down to 4 K. A compensation of the two sublattice magnetization is found at 75 K, a feature induced by the Al for Co substitution and not observed in the corresponding TmCo{sub 5} compound. Magnetization curves reveal large coercivity values at low temperature such as 2.48 T at 2 K.

  2. Optimization of CR-39 for fast neutron dosimetry applications

    CERN Document Server

    Vilela, E; Giacomelli, G; Giorgini, M; Morelli, B; Patrizii, L; Serra, P; Togo, V

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: sup 2 sup 4 sup 1 Am-Be, sup 2 sup 5 sup 2 Cf and sup 2 sup 3 sup 8 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose.

  3. Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester; Edward H. Seabury

    2008-08-01

    Active interrogation, a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material. The most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source. Exploiting the unique operating characteristics of these devices, including their monoenergetic neutron emissions and their ability to operate in pulsed modes, presents a number of options for performing prompt and delayed signature analyses using both photon and neutron sensors. A review of literature in this area shows multiple applications of the active neutron interrogation technique for performing nuclear nonproliferation measurements. Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material. This paper discusses the historical use of this technique and examines its context within the scope and challenges of next-generation nuclear fuel cycles and advanced concept nuclear fuel cycle facilities.

  4. Neutron-scattering experiment on solid 3He

    Science.gov (United States)

    Mat'aš, S.; Bat'ko, I.; Boyko, V.; Schöttl, S.; Siemensmeyer, K.; Raasch, S.; Radulov, I.; Adams, E. D.; Scherline, T. E.

    The central aim of our work is the characterisation of magnetic and crystallographic properties of solid 3He on a microscopic scale. This can only be achieved using neutron-diffraction techniques. The potential of neutron methods in magnetism and their application to nuclear magnetism is well known. They were very successful in the recent investigation of spontaneous nuclear order in copper and silver. The high neutron absorption cross section makes the application of neutron diffraction in solid 3He very difficult - but a careful feasibility study of diffraction experiments shows that new results of fundamental importance in the field of magnetism may be gained.

  5. A neutron diffraction study of the R{sub 15}Ge{sub 9}C compounds (R = Ce, Pr, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Tencé, S., E-mail: tence@icmcb-bordeaux.cnrs.fr [Université Grenoble Alpes, Institut Néel, BP166, F-38042 Grenoble (France); CNRS, Institut Néel, Rue des Martyrs, F-38042 Grenoble (France); Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux, 87 Avenue Docteur Albert Schweitzer, 33608 Pessac Cedex (France); Isnard, O. [Université Grenoble Alpes, Institut Néel, BP166, F-38042 Grenoble (France); CNRS, Institut Néel, Rue des Martyrs, F-38042 Grenoble (France); Wrubl, F. [Department of Chemistry, University of Genoa, Via Dodecaneso 31, 16146 Genoa (Italy); Manfrinetti, P. [Department of Chemistry, University of Genoa, Via Dodecaneso 31, 16146 Genoa (Italy); Institute SPIN – CNR, Corso Perrone 24, 16152 Genoa (Italy)

    2014-05-01

    Highlights: • Neutron diffraction study was performed on the germanides R{sub 15}Ge{sub 9}C (R = Ce, Pr, Nd). • The interstitial carbon atoms occupy mainly the site 2b in (1/3 2/3 ∼1/2). • The three compounds display canted ferromagnetic structures with k = [0 0 0]. • Carbon insertion strongly modifies the magnetic properties of the parent germanides. - Abstract: In this work we report the results of the neutron diffraction investigation performed on the germanides R{sub 15}Ge{sub 9}C, for R = Ce, Pr and Nd (La{sub 15}Ge{sub 9}Fe-type, hP50, P6{sub 3}mc, Z = 2), to refine the crystal superstructure of these compounds and determine their magnetic structures. The interstitial carbon atoms occupy mainly the 2b Wyckoff site in the position (1/3 2/3 ∼1/2) and also, with a smaller occupancy rate, the Wyckoff site 2a at (0 0 ∼1/2). In the magnetic state, the three compounds display predominantly a ferromagnetic behavior with the propagation vector k = [0 0 0]. These results are in agreement with the magnetization measurements, with T{sub C} = 10, 30 and 80 K as Curie temperature of Ce{sub 15}Ge{sub 9}C, Pr{sub 15}Ge{sub 9}C and Nd{sub 15}Ge{sub 9}C, respectively. Ce{sub 15}Ge{sub 9}C and Nd{sub 15}Ge{sub 9}C present a ferromagnetic alignment of the R moments along the c-axis and an antiferromagnetic spin arrangement within the (a–b) plane. For Pr{sub 15}Ge{sub 9}C the ferromagnetic contribution is found within the (a–b) plane, as previously observed for the isotypic compound Tb{sub 15}Si{sub 9}C. The carbides crystal structure possesses four inequivalent rare earth sites carrying different magnetic moments, leading to mean values of 0.9 μ{sub B}/Ce, 1.1 μ{sub B}/Pr and 2.2 μ{sub B}/Nd for Ce{sub 15}Ge{sub 9}C, Pr{sub 15}Ge{sub 9}C and Nd{sub 15}Ge{sub 9}C, respectively. The magnetic structures of these R{sub 15}Ge{sub 9}C compounds differ strongly from those of their parent R{sub 5}Ge{sub 3} germanides, but present strong similarities with the

  6. Advances in structure research by diffraction methods

    CERN Document Server

    Hoppe, W

    1974-01-01

    Advances in Structure Research by Diffraction Methods: Volume 5 presents discussions on application of diffraction methods in structure research. The book provides the aspects of structure research using various diffraction methods. The text contains 2 chapters. Chapter 1 reviews the general theory and experimental methods used in the study of all types of amorphous solid, by both X-ray and neutron diffraction, and the detailed bibliography of work on inorganic glasses. The second chapter discusses electron diffraction, one of the major methods of determining the structures of molecules in the

  7. In situ neutron powder diffraction study of phase-structural transformations in the La–Mg–Ni battery anode alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wan, ChuBin [University of Science and Technology Beijing, 100083 (China); Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway); Denys, R.V. [Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway); HYSTORSYS AS, P.O. Box 45, Kjeller NO-2027 (Norway); Yartys, V.A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway); Norwegian University of Science and Technology, Trondheim NO-7491 (Norway)

    2016-06-15

    This work was focused on studies of temperature-induced phase-structural transformations in the as-cast La{sub 2}MgNi{sub 9} metal hydride battery electrode alloy. The interactions in the alloy were studied by in situ neutron powder diffraction at temperatures ranging from 300 K to 1273 K. Initial alloy is multi-phase structured, containing six different intermetallics with five stoichiometric compositions. These include the targeted rhombohedral La{sub 2}MgNi{sub 9} as the main phase constituent, together with three electrochemically active intermetallics, La{sub 3}MgNi{sub 14} (3R), La{sub 4}MgNi{sub 19} (2H) and La{sub 4}MgNi{sub 19} (3R). Furthermore, the alloy contained two “ballast” intermetallics, LaNi{sub 5} and LaMgNi{sub 4}. Various transformations take place on heating, leading to the significant changes in the contents of the constituent intermetallics, first of all to the disappearance of LaNi{sub 5} and LaMgNi{sub 4}. Thermal volume expansions of the studied intermetallics were well fitted by the linear dependences and resulted in similar values of 4.3–5.5 vol.% at 1223 K as compared to 300 K. - Highlights: • Transformations in the as-cast La{sub 2}MgNi{sub 9} were studied by in situ NPD at 300–1273 K. • Initial alloy contains 6 different intermetallics with 5 stoichiometric compositions. • On heating LaNi{sub 5} and LaMgNi{sub 4} disappear first. • Thermal volume expansions have similar values of 4–5 vol.% at 1223 K vs 300 K. • Optimization of the La–Mg–Ni MH alloys as battery anodes is guided by the results.

  8. Neutron powder thermo-diffraction in mechanically alloyed Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro, E-mail: pgorria@uniovi.e [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Martinez-Blanco, David [Unidad de Magnetometria, SCT' s, Universidad de Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2010-04-16

    Nanostructured Fe{sub 64}Ni{sub 36} alloy has been obtained using high-energy ball milling for 35 h of milling time, Fe{sub 64}Ni{sub 36} MA-35 h. The initial as-milled Fe{sub 64}Ni{sub 36} MA-35 h powders are inhomogeneous, showing a majority phase with a face-centred cubic (fcc) crystal structure [88(2)%] and a minority phase with body-centred cubic (bcc) crystal structure [7(2)%]. The evolution of the microstructure with temperature between 300 K and 1100 K has been followed by means of in situ neutron powder thermo-diffraction experiments. The room temperature values for the mean crystalline size and the mechanical-induced microstrain of the fcc phase in the as-milled sample are {approx}10 nm and {approx}0.7%, respectively. Moreover, after heating the Fe{sub 64}Ni{sub 36} MA-35 h powders up to 1100 K, an increase of around 65 K in the Curie temperature respect to that of the commercial coarse-grained alloy of the same composition is observed. The latter together with the observed temperature dependence of the lattice parameter suggests that the Fe{sub 64}Ni{sub 36} MA-35 h sample subjected to the heating process exhibits invar behaviour. On heating up to 1100 K thermal relaxation of the microstructure occurs giving rise to grain growth above 100 nm, nearly vanishing values for the maximum strain, and the transformation of the bcc phase into the fcc one above 800 K, being the latter stable in subsequent heating-cooling processes.

  9. Structure of Nb2O5-NaPO3 glasses by X-ray and neutron diffraction.

    Science.gov (United States)

    Hoppe, U; Delevoye, L; Montagne, L; Zimmermann, M v; Hannon, A C

    2013-06-14

    X-ray and neutron diffraction of excellent resolving power are used to determine the atomic structure of niobium phosphate glasses. These studies complement the results of earlier (31)P and (93)Nb nuclear magnetic resonance, Raman scattering and O1s X-ray photoelectron spectroscopy of the (Nb2O5)x-(NaPO3)(1-x) glasses (0 ≤ x ≤ 0.40). The Nb-O distances behave uniformly for glasses of 0.08 ≤ x ≤ 0.20 with distorted NbO6 octahedra that are characterized by a corner with a short Nb-O bond of 0.174 nm, four bonds of ~0.20 nm and a longer bond. The concomitant change of PO4 units from chain to end groups extends likewise to glasses of x = ~0.20, i.e. only one O atom per Nb contributes to the rupture of phosphate chains. This behaviour differs from that of related crystal structures and phosphate glasses of other oxide additions. Asymmetric Nb-O-Nb bridges that include the short Nb-O bond are formed for glasses of x ≤ 0.20 while symmetric bridges with two Nb-O bonds of ~0.190 nm appear for x > 0.2. A pre-peak at 8 nm(-1) is found in the S(Q) for glasses of 0.08 ≤ x ≤ 0.20 which is interpreted as the presence of niobate and sodium phosphate micro-domains. The weakness of this pre-peak if it is compared with that of similar GeO2-KPO3 glasses is explained with modifications of the micro-domain structure by a fraction of non-bridging O in Nb-O···Na(+) sites. The pre-peak vanishes for the glass of x = 0.40.

  10. High-sensitivity neutron diffraction of membranes: Location of the Schiff base end of the chromophore of bacteriorhodopsin.

    Science.gov (United States)

    Heyn, M P; Westerhausen, J; Wallat, I; Seiff, F

    1988-04-01

    THREE IMPORTANT EVENTS IN THE FUNCTIONAL CYCLE OF BACTERIORHODOPSIN OCCUR AT THE CHROMOPHORE: the primary absorption of light, the isomerization from the alltrans to the 13-cis form, and the deprotonation and reprotonation of its Schiff base. The protonated Schiff base linkage of the chromophore with lysine-216 plays an essential role in the color regulation of the pigment and is most likely directly involved in the charge translocation of this light-driven proton pump. Although much is known about the structure of the protein, the position of this key functional group has not yet been determined. We have synthesized a retinal in which the five protons closest to the Schiff base are replaced by deuterons. The labeled retinal was spontaneously incorporated into bacteriorhodopsin by using a mutant of Halobacterium halobium that is deficient in the synthesis of retinal. The position of the labeled Schiff base end of the chromophore was determined in the two-dimensional projected density of dark-adapted bacteriorhodopsin by neutron diffraction. The result fits very well with our previous work using retinals that were selectively deuterated in the middle of the polyene chain or in the cyclohexene ring. A coherent structure emerges with the three labeled positions on one line, separated by distances that are in good agreement with the tilt angle of the polyene chain (about 20 degrees ). The chromophore is located in the interior of the protein with the nitrogen of the Schiff base between helices 2 and 6 and with its ring in the vicinity of helix 4. Our results show that it is possible to locate a small group containing as few as five deuterons in a membrane protein of molecular weight 27,000.

  11. High-sensitivity neutron diffraction of membranes: Location of the Schiff base end of the chromophore of bacteriorhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Heyn, M.P.; Westerhausen, J.; Wallat, I.; Seiff, F. (Freie Universitaet Berlin (West Germany))

    1988-04-01

    Three important events in the functional cycle of bacteriorhodopsin occur at the chromophore: the primary absorption of light, the isomerization from the all-trans to the 13-cis form, and the deprotonation and reprotonation of its Schiff base. The protonated Schiff base linkage of the chromophore with lysine-216 plays an essential role in the color regulation of the pigment and is most likely directly involved in the charge translocation of this light-driven proton pump. Although much is known about the structure of the protein, the position of this key functional group has not yet been determined. The authors have synthesized a retinal in which the five protons closest to the Schiff base are replaced by deuterons. The labeled retinal was spontaneously incorporated into bacteriorhodopsin by using a mutant of Halobacterium halobium that is deficient in the synthesis of retinal. The position of the labeled Schiff base end of the chromophore was determined in the two-dimensional projected density of dark-adapted bacteriorhodopsin by neutron diffraction. The result fits very well with their previous work using retinals that were selectively deuterated in the middle of the polyene chain or in the cyclohexene ring. A coherent structure emerges with the three labeled positions on one line, separated by distances that are in good agreement with the tilt angle of the polyene chain (about 20{degree}). The results show that it is possible to locate a small group containing as few as five deuterons in a membrane protein of molecular weight 27,000.

  12. In operando neutron diffraction study of LaNdMgNi9H13 as a metal hydride battery anode

    Science.gov (United States)

    Nazer, N. S.; Denys, R. V.; Yartys, V. A.; Hu, Wei-Kang; Latroche, M.; Cuevas, F.; Hauback, B. C.; Henry, P. F.; Arnberg, L.

    2017-03-01

    La2MgNi9-related alloys are superior metal hydride battery anodes as compared to the commercial AB5 alloys. Nd-substituted La2-yNdyMgNi9 intermetallics are of particular interest because of increased diffusion rate of hydrogen and thus improved performance at high discharge currents. The present work presents in operando characterization of the LaNdMgNi9 intermetallic as anode for the nickel metal hydride (Ni-MH) battery. We have studied the structural evolution of LaNdMgNi9 during its charge and discharge using in situ neutron powder diffraction. The work included experiments using deuterium gas and electrochemical charge-discharge measurements. The alloy exhibited a high electrochemical discharge capacity (373 mAh/g) which is 20% higher than the AB5 type alloys. A saturated β-deuteride synthesized by solid-gas reaction at PD2 = 1.6 MPa contained 12.9 deuterium atoms per formula unit (D/f.u.) which resulted in a volume expansion of 26.1%. During the electrochemical charging, the volume expansion (23.4%) and D-contents were found to be slightly reduced. The reversible electrochemical cycling is performed through the formation of a two-phase mixture of the α-solid solution and β-hydride phases. Nd substitution contributes to the high-rate dischargeability, while maintaining a good cyclic stability. Electrochemical Impedance Spectroscopy (EIS) was used to characterize the anode electrode on cycling. A mathematical model for the impedance response of a porous electrode was utilized. The EIS showed a decreased hydrogen transport rate during the long-term cycling, which indicated a corresponding slowing down of the electrochemical processes at the surface of the metal hydride anode.

  13. Neutron diffraction and electrochemical studies of Na0.79(Co,Mn)O2 cathodes for sodium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Faith R [National Energy Technology Laboratory (NETL); Cheng, Yongqiang [ORNL; Feygenson, Mikhail [ORNL; Bridges, Craig A [ORNL; Moorhead-Rosenberg, Z [Oak Ridge National Laboratory (ORNL); Manthiram, Arumugam [University of Texas at Austin; Goodenough, J. B. [University of Texas at Austin; Paranthaman, Mariappan Parans [ORNL; Manivannan, A. [National Energy Technology Laboratory (NETL)

    2014-01-01

    Na0.79CoO2 and Na0.79Co0.7Mn0.3O2 with a layered hexagonal structure (P2-type) were synthesized by the Pechini process followed by heat treatment at elevated temperatures in order to achieve the crystalline phases. The samples were characterized with x-ray diffraction, neutron diffraction, magnetic measurements and electrochemical charge-discharge cycling. X-ray diffraction confirmed the P2 layered hexagonal structure after heat treatment at 900 C in air. Neutron diffraction patterns confirm Mn doping on Co sites without forming pronounced Mn-Co ordering. Cyclic voltammetry showed the oxidation and reduction peaks of Co and Mn, indicating the intercalation and de-intercalation behavior of the Na ions. A discharge capacity of 60 mAh/g was achieved for both the compositions, with the Na0.79Co0.70Mn0.3O2 composition showing a more stable discharge capacity up to 60 cycles.

  14. NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Diprete, D; C Diprete, C; Raymond Sigg, R

    2006-08-14

    NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

  15. A Neutron-Diffraction Study of the Solid Layers at the Liquid Solid Boundary in 4He-Films Adsorbed on Graphite

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Passell, L.; Thomlinson, W.

    1981-01-01

    A neutron scattering study of the structure of 4He films adsorbed on graphite is reported. Diffraction from helium monolayers at a temperature of 1.2K shows the formation of an incommensurate, triangular-lattice solid of high density. As the coverage is increased above two layers, the diffraction...... pattern changes indicating solidification of a second layer. The observed two-layer patterns can be indexed with either a pair of incommensurate, triangular-lattice solid layers of different densities or a close-packed bilayer; the experimental information available is not sufficient to make a more...... precise identification. A measurement of the height of the first helium layer above the graphite basal plane was also made. This was done by determining the coverage-dependent shift in the position of the graphite (002) diffraction peak (assumed to arise from interference between film and substrate...

  16. Characterization of silicon carbide and diamond detectors for neutron applications

    Science.gov (United States)

    Hodgson, M.; Lohstroh, A.; Sellin, P.; Thomas, D.

    2017-10-01

    The presence of carbon atoms in silicon carbide and diamond makes these materials ideal candidates for direct fast neutron detectors. Furthermore the low atomic number, strong covalent bonds, high displacement energies, wide bandgap and low intrinsic carrier concentrations make these semiconductor detectors potentially suitable for applications where rugged, high-temperature, low-gamma-sensitivity detectors are required, such as active interrogation, electronic personal neutron dosimetry and harsh environment detectors. A thorough direct performance comparison of the detection capabilities of semi-insulating silicon carbide (SiC–SI), single crystal diamond (D–SC), polycrystalline diamond (D–PC) and a self-biased epitaxial silicon carbide (SiC–EP) detector has been conducted and benchmarked against a commercial silicon PIN (Si–PIN) diode, in a wide range of alpha (Am-241), beta (Sr/Y-90), ionizing photon (65 keV to 1332 keV) and neutron radiation fields (including 1.2 MeV to 16.5 MeV mono-energetic neutrons, as well as neutrons from AmBe and Cf-252 sources). All detectors were shown to be able to directly detect and distinguish both the different radiation types and energies by using a simple energy threshold discrimination method. The SiC devices demonstrated the best neutron energy discrimination ratio (E\\max (n=5 MeV)/E\\max (n=1 MeV)  ≈5), whereas a superior neutron/photon cross-sensitivity ratio was observed in the D–PC detector (E\\max (AmBe)/E\\max (Co-60)  ≈16). Further work also demonstrated that the cross-sensitivity ratios can be improved through use of a simple proton-recoil conversion layer. Stability issues were also observed in the D–SC, D–PC and SiC–SI detectors while under irradiation, namely a change of energy peak position and/or count rate with time (often referred to as the polarization effect). This phenomenon within the detectors was non-debilitating over the time period tested (> 5 h) and, as such, stable

  17. Fusion Based Neutron Sources for Security Applications: Energy Optimisation

    OpenAIRE

    Albright, S.; Seviour, Rebecca

    2014-01-01

    There is a growing interest in the use of neutrons for na- tional security. The majority of work on security focuses on the use of either sealed tube DT fusors or fission sources, e.g. Cf-252. Fusion reactions enable the energy of the neu- tron beam to be chosen to suit the application, rather than the application being chosen based on the available neu- tron beam energy. In this paper we discuss simulations of fusion reactions demonstrating the broad range of energies available and methods f...

  18. Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

    Science.gov (United States)

    Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

    2010-01-14

    The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

  19. Dy-IP characterization and its application for experimental neutron radiography tests under realistic conditions

    Science.gov (United States)

    Tamaki, Masayoshi; Iida, Kazuhiro; Mori, Noriaki; Lehmann, Eberhard H.; Vontobel, Peter; Estermann, Mirko

    2005-04-01

    Imaging plates containing Dy for neutron radiography have been designed, fabricated and tested experimentally. Using the imaging plates combined with the developed NR system and the honeycomb collimator, quantitative neutron radiograph, which is free from scattered neutron and γ-ray, has been obtained. Application has been conducted for the post-irradiation examination for the nuclear fuel pin.

  20. The review of the application of neutron radiography to thermal hydraulic research

    CERN Document Server

    Mishima, K; Saitô, Y; Nakamura, H; Matsubayashi, M

    1999-01-01

    This paper is concerned with the establishment of thermal neutron radiography as a high accuracy measurement method. This paper reviews the present status on the development of high-frame-rate neutron radiography with a steady thermal neutron beam and its application to multiphase flow research performed at the Research Reactor Institute of Kyoto University in collaboration with the Japan Atomic Energy Research Institute.

  1. Measurements of neutron-induced reactions in inverse kinematics and applications to nuclear astrophysics

    OpenAIRE

    2015-01-01

    Neutron capture cross sections of unstable isotopes are important for neutron-induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes. The idea is to measure neutron-induced reactions on radioactive ions in inverse kinematics. This means, the radioactive ions will ...

  2. Advances in neutron radiographic techniques and applications: a method for nondestructive testing.

    Science.gov (United States)

    Berger, Harold

    2004-10-01

    A brief history of neutron radiography is presented to set the stage for a discussion of significant neutron radiographic developments and an assessment of future directions for neutron radiography. Specific advances are seen in the use of modern, high dynamic range imaging methods (image plates and flat panels) and for high contrast techniques such as phase contrast, and phase-sensitive imaging. Competition for neutron radiographic inspection may develop as these techniques offer application prospects for X-ray methods.

  3. Quantum interferences revealed by neutron diffraction accord with a macroscopic-scale quantum-theory of ferroelectrics KH2(1- ρ)D2 ρ PO4

    Science.gov (United States)

    Fillaux, François; Cousson, Alain

    2016-03-01

    Neutron diffraction by single-crystals KH2(1- ρ)D2 ρ PO4 at 293 K reveal quantum interferences consistent with a static lattice of entangled proton-deuteron scatterers. These crystals are represented by a macroscopic-scale condensate of phonons with continuous space-time-translation symmetry and zero-entropy. This state is energetically favored and decoherence-free over a wide temperature-range. Projection of the crystal state onto a basis of four electrically- and isotopically-distinct state-vectors accounts for isotope and pressure effects on the temperature of the ferroelectric-dielectric transition, as well as for the latent heat. At the microscopic level, an incoming wave realizes a transitory state either in the space of static positional parameters (elastic scattering) or in that of the symmetry species (energy transfer). Neutron diffraction, vibrational spectroscopy, relaxometry and neutron Compton scattering support the conclusion that proton and deuteron scatterers are separable exclusively through resonant energy-transfer.

  4. Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction

    CERN Document Server

    Marmotti, M; Kampmann, R

    2002-01-01

    Two-dimensional position-sensitive gaseous detectors have been developed at the Geesthacht Neutron Facility (GeNF) for high-resolution neutron and X-ray diffractometry. They are multi-wire proportional counters with delay-line readout and sensitive areas of 300 mm x 300 mm or 500 mm x 500 mm. For detecting X-rays, neutrons and hard X-rays the counters are filled with Ar/CO sub 2 , sup 3 He/CF sub 4 and Xe/CO sub 2 , respectively. One neutron detector is used at the ARES diffractometer at GKSS, which is dedicated to the analysis of residual stresses. Further ones are used for analysing textures and residual stresses at the hard-X-ray beamline PETRA-2 at HASYLAB, and one detector is being developed for the neutron reflectometer REFSANS at the research reactor FRM-II in Munich, Germany. (orig.)

  5. Texture Analysis using The Neutron Diffraction Method on The Non Standardized Austenitic Steel Process by Machining,Annealing, and Rolling

    Directory of Open Access Journals (Sweden)

    Tri Hardi Priyanto

    2016-04-01

    Full Text Available Austenitic steel is one type of stainless steel which is widely used in the industry. Many studies on  austenitic stainless steel have been performed to determine the physicalproperties using various types of equipment and methods. In this study, the neutron diffraction method is used to characterize the materials which have been made from  minerals extracted from the mines in Indonesia. The materials consist of a granular ferro-scrap, nickel, ferro-chrome, ferro-manganese, and ferro-silicon added with a little titanium. Characterization of the materials was carried out in threeprocesses, namely: machining, annealing, and rolling. Experimental results obtained from the machining process generally produces a texture in the 〈100〉direction. From the machining to annealing process, the texture index decreases from 3.0164 to 2.434.Texture strength in the machining process (BA2N sample is  8.13 mrd and it then decreases to 6.99 in the annealing process (A2DO sample. In the annealing process the three-component texture appears, cube-on-edge type texture{110}〈001〉, cube-type texture {001}〈100〉, and brass-type {110}〈112〉. The texture is very strong leading to the direction of orientation {100}〈001〉, while the {011}〈100〉is weaker than that of the {001}, and texture withorientation {110}〈112〉is weak. In the annealing process stress release occurred, and this was shown by more randomly pole compared to stress release by the machining process. In the rolling process a brass-type texture{110}〈112〉with a spread towards the goss-type texture {110}〈001〉 appeared,  and  the  brass  component  is markedly  reinforced  compared  to  the undeformed state (before rolling. Moreover, the presence of an additional {110} component was observed at the center of the (110 pole figure. The pole density of three components increases withthe increasing degree of thickness reduction. By increasing degrees

  6. Compact D-D/D-T neutron generators and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Tak Pui [Univ. of California, Berkeley, CA (United States)

    2003-01-01

    Neutron generators based on the 2H(d,n)3He and 3H(d,n)4He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >109 n/s has been obtained with a D-D coaxial neutron source. Several potential applications were investigated by using computer simulations. The computer code used for simulations and the variance reduction techniques employed were discussed. A study was carried out to determine the neutron flux and resolution of a D-T neutron source in thermal neutron scattering applications for condensed matter experiments. An error analysis was performed to validate the scheme used to predict the resolution. With a D-T neutron yield of 1014 n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 105 n/cm2s. It was found that the resolution of cold neutrons was better than that of thermal neutrons when the duty factor is high. This neutron generator could be efficiently used for research and educational purposes at universities. Additional applications studied were positron production and

  7. Compact D-D/D-T neutron generators and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Tak Pui

    2003-05-01

    Neutron generators based on the {sup 2}H(d,n){sup 3}He and {sup 3}H(d,n){sup 4}He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >10{sup 9} n/s has been obtained with a D-D coaxial neutron source. Several potential applications were investigated by using computer simulations. The computer code used for simulations and the variance reduction techniques employed were discussed. A study was carried out to determine the neutron flux and resolution of a D-T neutron source in thermal neutron scattering applications for condensed matter experiments. An error analysis was performed to validate the scheme used to predict the resolution. With a D-T neutron yield of 10{sup 14} n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 10{sup 5} n/cm{sup 2}s. It was found that the resolution of cold neutrons was better than that of thermal neutrons when the duty factor is high. This neutron generator could be efficiently used for research and educational purposes at universities. Additional applications studied were positron production and Boron Neutron Capture Therapy (BNCT). The

  8. Crystal structure and magnetism of YbFeMnO 5: A neutron diffraction and Mössbauer spectroscopy study

    Science.gov (United States)

    Martínez-Lope, M. J.; Retuerto, M.; Alonso, J. A.; García-Hernández, M.; Krezhov, K.; Spirov, I.; Ruskov, T.; Fernández-Díaz, M. T.

    2009-04-01

    We have studied the crystal structure and magnetic properties of Y bFeMnO 5 obtained by substituting Fe 3+ for Mn 3+ in the parent Y bMn 2O 5 compound, through x-ray (XRD) and neutron (NPD) powder diffraction, magnetometry and Mössbauer spectroscopy. The samples were prepared in polycrystalline form by a soft chemistry route, followed by thermal treatments under high-oxygen pressure. The Rietveld analysis of diffraction data shows that Y bFeMnO 5 is isostructural with the oxides of stoichiometry RMn 2O 5 (R=rare earth, Y or Bi); the crystal structure is orthorhombic, Pbam space group, formed by chains of edge-sharing Mn 4+O 6 octahedra linked together by dimer groups of square pyramids Fe 3+O 5 and Y b 3+O 8 scalenohedra. A low level of disorder was established between the two transition metal positions 4 f and 4 h, occupied ideally by Mn 4+ and by Fe 3+: about 6% of Mn cations is replaced by Fe and 16% of Fe by Mn. Mössbauer spectroscopy data confirm the existence of two distinct crystallographic sites for Fe 3+. One of them corresponds to almost regular octahedra (at 4 f positions), characterized by nearly equal Mn/Fe-O distances of 1.890 Å at RT (from NPD data), giving a quadrupole doublet in the Mössbauer spectra at RT, broadened by the Fe/Mn disorder over this site. The second environment for Fe 3+ contributes to a less broadened, but more intensive doublet in the Mössbauer spectra, which corresponds to a distorted square pyramid Fe 3+O 5 (at 4h sites), for which NPD data demonstrates an axial distortion with three sets of Fe-O distances at 2.010(2) Å, 1.859(5) Å and 1.925(3) Å. Magnetic studies and the thermal evolution of the NPD patterns show that below a transition temperature Tc˜178 K a long-range magnetic order is developed, resolved from NPD data as a ferrimagnetic structure with propagation vector k=0. The spin arrangements for the Mn 4+ ions ( 4f site) and Fe 3+ ions ( 4h site) are given by the basis vectors ( 0,0,Fz) and ( 0,0,Fz

  9. An in situ powder neutron diffraction study of nano-precipitate formation during processing of oxide-dispersion-strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongtao, E-mail: hongtao.zhang@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Chong, Kok Boon; Fitzpatrick, Michael E. [Materials Engineering, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Roberts, Steve G.; Grant, Patrick S. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2014-01-05

    Highlights: • In situ powder neutron diffraction to study precipitate formation in ODS steel. • First real time observation of nano-precipitate formation during processing. • Y{sub 2}O{sub 3} particles were fully dissolved into steel matrix during mechanical alloy. • The precipitation occurred during annealing of as-milled powder above 900 °C. -- Abstract: The evolution of phases in a Fe–14Cr–10Y{sub 2}O{sub 3} (wt%) oxide-dispersion-strengthened ferritic steel during mechanical alloying (MA) and subsequent annealing was studied by high resolution powder neutron diffraction, with emphasis on the kinetics of oxide-based nano-precipitate formation. Y{sub 2}O{sub 3} particles were completely dissolved into the ferritic matrix during MA. The formation of nano-precipitates was then observed by in situ thermo-diffraction experiments during annealing of as-milled powder above 900 °C, supported by scanning electron microscopy. This revealed nano-precipitate coarsening with increasing annealing temperature. Powder microhardness was measured at various processing stages, and hardness changes are discussed in terms of the measured phase fractions, crystallite size and lattice strain at different temperatures and times.

  10. Crystallographic and magnetic structure in spinel system FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Soon Son, Bae [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Jin Kim, Sam [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Shim, In-Bo [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Wha Lee, Bo [Department of Physics, Hankuk University of Foreign Studies, Yongin, Kyungki, 449-791 (Korea, Republic of); Sung Kim, Chul [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of)]. E-mail: cskim@phys.kookmin.ac.kr

    2006-09-15

    The samples of FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} (x=0.1, 0.3) were prepared by solid reaction method. The crystallographic structure and the magnetic properties of the obtained compounds were investigated by X-ray and neutron powder diffraction, vibrating sample magnetometer (VSM), and Moessbauer spectroscopy. The Cr ions occupy 16(d) site exclusively, while mixed spinel behaviors are developed with increase of Ga ions. Finally, it induces a large quadrupole splitting in octahedral (16d) sites. Neutron diffraction on FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} above 10 K shows that there is no crystallographic distortion and reveals antiferromagnetic ordering. The magnetic moment of Fe{sup 2+} (3.45 {mu} {sub B}) are found to be aligned antiparallel to Cr{sup 3+} (-2.89 {mu} {sub B}), in the sample x=0.1. Below the Neel temperature, magnetic peaks exist on the crystal diffraction peaks. It proves that spin structure of the same species are aligned parallel.

  11. Negative thermal expansion in the Russian blue analog Zn3[Fe(CN)6]2: x-ray diffraction and neutron vibrational studies

    Energy Technology Data Exchange (ETDEWEB)

    Nakotte, Heinz [Los Alamos National Laboratory; Daemen, Luke [Los Alamos National Laboratory; Adak, Sourav [Los Alamos National Laboratory

    2009-01-01

    The cubic Prussian Blue (PB) analog, Zn{sub 3} [Fe(CN){sub 6}]{sub 2}, has been studied by X-ray powder diffraction and inelastic neutron scattering (INS). X-ray data collected at 300 and 84 K revealed negative thermal expansion (NTE) behavior for this material. The NTE coefficient was found to be -31.1 x 10{sup -6} K{sup -1}. The neutron vibrational spectrum for Zn{sub 3}[Fe(CN){sub 6}]{sub 2}.xH{sub 2}O, was studied in detail. The INS spectrum showed well-defined, well-separated bands corresponding to the stretching of and deformation modes of the Fe and Zn octahedra, all below 800 cm{sup -1}.

  12. Agglomeration and Sintering in Annealed FePt Nanoparticle Assemblies Studied by Small Angle Neutron Scattering and X-Ray Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, T.

    2005-01-03

    In this work we give a detailed account of the use of small angle neutron scattering to study the properties of polymer mediated, self assembled nanoparticle arrays as a function of annealing temperature. The results from neutron scattering are compared with those obtained from x-ray diffraction. Both techniques show that particle size increases with annealing temperatures of 580 C and above. They also show that the distribution of particle diameters is significant and increases with annealing temperature. The complementary nature of the two measurements allows a comprehensive structural model of the assemblies to be developed in terms of particle sintering and agglomeration. To realize the potential of nanoparticle assemblies as a monodispersed data storage medium the problem of particle separation necessary to avoid sintering and agglomeration during annealing must be addressed.

  13. Magnetic properties of PrX 2 compounds (X = Pt, Rh, Ru, Ir) studied by hyperfine specific heat, magnetization and neutron-diffraction measurements

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Fischer, P.; Furrer, A.; Buschow, K. H. J.

    1983-04-01

    Magnetic ordering phenomena in rare-earth intermetallic compounds can be unravelled most advantageously in the case of simple crystallographic structure and when a combination of microscopic techniques is applied. Here we shall present the temperature and magnetic field dependence of the magnetic moment of the cubic PrX 2 compounds (X = Pt, Rh, Ru, Ir), as inferred from hyperfine specific-heat, magnetization and neutron-diffraction measurements. The results are compared with a mean-field calculation, taking crystalline electric field and bilinear (dipolar) exchange interactions into account. Adopting experimental values of the Lea, Leask and Wolf parameters x and W from inelastic neutron scattering results, we find satisfactory agreement between our magnetic data and the mean-field theory. An observed discrepancy of about 15% between the calculated and measured saturation values of the spontaneous magnetization can be explained by the presence of quadrupolar interactions.

  14. Diffraction studies applicable to 60-foot microwave research facilities

    Science.gov (United States)

    Schmidt, R. F.

    1973-01-01

    The principal features of this document are the analysis of a large dual-reflector antenna system by vector Kirchhoff theory, the evaluation of subreflector aperture-blocking, determination of the diffraction and blockage effects of a subreflector mounting structure, and an estimate of strut-blockage effects. Most of the computations are for a frequency of 15.3 GHz, and were carried out using the IBM 360/91 and 360/95 systems at Goddard Space Flight Center. The FORTRAN 4 computer program used to perform the computations is of a general and modular type so that various system parameters such as frequency, eccentricity, diameter, focal-length, etc. can be varied at will. The parameters of the 60-foot NRL Ku-band installation at Waldorf, Maryland, were entered into the program for purposes of this report. Similar calculations could be performed for the NELC installation at La Posta, California, the NASA Wallops Station facility in Virginia, and other antenna systems, by a simple change in IBM control cards. A comparison is made between secondary radiation patterns of the NRL antenna measured by DOD Satellite and those obtained by analytical/numerical methods at a frequency of 7.3 GHz.

  15. Structural and chemical evolution of Fe-Co-O based ceramics under reduction/oxidation--an in situ neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Li Yaping; Maxey, Evan R.; Richardson, James W.; Ma Beihai

    2004-01-15

    Air-sintered ceramic samples in composition CoO{center_dot}nFe{sub 2}O{sub 3} (n=1 and 2) were prepared in solid-state reactions, resulting in a single spinel phase with composition CoFe{sub 2}O{sub 4}, and a two-phase mixture of identical spinel with {alpha}-Fe{sub 2}O{sub 3} for n=1 and 2, respectively. Their structural and chemical evolution over pO{sub 2} range of 10{sup -0.9} to 10{sup -19} atm was investigated using in situ neutron diffraction at isothermal condition ({approx}900 deg. C). Neutron diffraction data were analyzed through Rietveld refinements. The following sequences of structural transformation from {alpha}-Fe{sub 2}O{sub 3} hematite{yields}(Fe,Co)-spinel{yields}(Fe,Co){sub 1-x}O wustite{yields}(Fe,Co)O rocksalt{yields}{gamma}-(Fe,Co){yields}{alpha}-(Fe,Co){yields}({gamma}-(Fe,Co)) were observed on the reduction of Fe-Co-O based ceramics. With the development of reduction at pO{sub 2} down to 10{sup -15} atm, mixed valence (Fe{sup 2+} and Fe{sup 3+}) spinel was first formed in Fe-excess (Fe, Co) spinel phases. The intermediate phases were usually Co-rich compared with their parent mixed oxide phases. Particularly, the initial metallic precipitate is Co-rich {gamma}, independent of initial stoichiometry. Reduction kinetics at pO{sub 2} of {approx}10{sup -19} atm is extremely fast, but crystalline form and structural integrity are maintained. As crystal structures of the various involved phases are very similar, few structural blocks were disturbed as oxygen was released from the samples. In addition, re-oxidation behavior of reduced products was also studied, and phase composition and microstructure of post-neutron experiments were characterized by X-ray diffraction and scanning electron microscopy.

  16. New applications of neutron noise theory in power reactor physics

    Energy Technology Data Exchange (ETDEWEB)

    Arzhanov, Vasiliy

    2000-04-01

    The present thesis deals with neutron noise theory as applied to three comparatively different topics (or problems) in power reactor physics. Namely they are: theoretical investigation of the possibility to use a newly proposed current-flux (C/F) detector in Pressurized Water Reactors (PWRs) for the localisation of anomalies; both definition and studies on the point kinetic and adiabatic approximations for the relatively recently proposed Accelerator Driven Systems (ADS); development of the general theory of linear reactor kinetics and neutron noise in systems with varying size. One important practical problem is to detect and localise a vibrating control rod pin. The significance comes from the operational experience which indicates that individual pins can execute excessive mechanical vibrations that may lead to damage. Such mechanical vibrations induce neutron noise that can be detected. While the detection is relatively easy, the localisation of a vibrating control rod is much more complicated because only one measuring position is available and one needs to have at least three measured quantities. Therefore it has currently been proposed that the fluctuations of the neutron current vector, called the current noise, can be used in addition to the scalar noise in reactor diagnostic problems. The thesis investigates the possibility of the localization of a vibrating control rod pin in a PWR control assembly by using the scalar neutron noise and the 2-D radial current noise as measured at one central point in the control assembly. An explicit localisation technique is elaborated in which the searched position is determined as the absolute minimum of a minimisation function. The technique is investigated in numerical simulations. The results of the simulation tests show the potential applicability of the method. By design accelerator-driven systems would operate in a subcritical mode with a strong external source. This calls for a revision of many concepts and

  17. When combined X-ray and polarized neutron diffraction data challenge high-level calculations: spin-resolved electron density of an organic radical.

    Science.gov (United States)

    Voufack, Ariste Bolivard; Claiser, Nicolas; Lecomte, Claude; Pillet, Sébastien; Pontillon, Yves; Gillon, Béatrice; Yan, Zeyin; Gillet, Jean Michel; Marazzi, Marco; Genoni, Alessandro; Souhassou, Mohamed

    2017-08-01

    Joint refinement of X-ray and polarized neutron diffraction data has been carried out in order to determine charge and spin density distributions simultaneously in the nitronyl nitroxide (NN) free radical Nit(SMe)Ph. For comparison purposes, density functional theory (DFT) and complete active-space self-consistent field (CASSCF) theoretical calculations were also performed. Experimentally derived charge and spin densities show significant differences between the two NO groups of the NN function that are not observed from DFT theoretical calculations. On the contrary, CASSCF calculations exhibit the same fine details as observed in spin-resolved joint refinement and a clear asymmetry between the two NO groups.

  18. Structure and phase transitions of monolayers of intermediate-length n-alkanes on graphite studied by neutron diffraction and molecular dynamics simulation

    DEFF Research Database (Denmark)

    Diama, A.; Matthies, B.; Herwig, K. W.;

    2009-01-01

    We present evidence from neutron diffraction measurements and molecular dynamics (MD) simulations of three different monolayer phases of the intermediate-length alkanes tetracosane (n-C24H50 denoted as C24) and dotriacontane (n-C32H66 denoted as C32) adsorbed on a graphite basal-plane surface. Our...... show evidence of broadening of the lamella boundaries as a result of molecules diffusing parallel to their long axis. At still higher temperatures, they indicate that the introduction of gauche defects into the alkane chains drives a melting transition to a monolayer fluid phase as reported previously...

  19. Structure of a fluid dioleoylphosphatidylcholine bilayer determined by joint refinement of x-ray and neutron diffraction data. II. Distribution and packing of terminal methyl groups.

    OpenAIRE

    Wiener, M C; White, S H

    1992-01-01

    We continue in this paper the presentation of theoretical and experimental methods for the joint refinement of neutron and x-ray lamellar diffraction data for the analysis of fluid (L alpha phase) bilayer structure (Wiener, M. C., and S. H. White. 1991 a, b, c. Biophys. J. 59:162-173 and 174-185; Biochemistry. 30:6997-7008; Wiener, M. C., G. I. King, and S. H. White. Biophys. J. 60: 568-576). We show how to obtain the distribution and packing of the terminal methyls in the interior of a fluid...

  20. Change in the magnetic structure of (Bi,Sm)FeO{sub 3} thin films at the morphotropic phase boundary probed by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Shingo; Anbusathaiah, Varatharajan; Takeuchi, Ichiro [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States); Fennell, Amy [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Enderle, Mechthild [Institut Laue Langevin, BP 156, 38042 Grenoble (France); Ratcliff, William D., E-mail: william.ratcliff@nist.gov [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2014-11-01

    We report on the evolution of the magnetic structure of BiFeO{sub 3} thin films grown on SrTiO{sub 3} substrates as a function of Sm doping. We determined the magnetic structure using neutron diffraction. We found that as Sm increases, the magnetic structure evolves from a cycloid to a G-type antiferromagnet at the morphotropic phase boundary, where there is a large piezoelectric response due to an electric-field induced structural transition. The occurrence of the magnetic structural transition at the morphotropic phase boundary offers another route towards room temperature multiferroic devices.