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1

Pulsed Neutron Powder Diffraction  

Science Journals Connector (OSTI)

The nature and scope of powder diffraction with a white, pulsed beam of neutrons is discussed. Analysis of the data by the Rietveld profile technique is described in brief, and a range of applications in solid...

A. K. Cheetham

1988-01-01T23:59:59.000Z

2

Magnetic Structure Analysis from Neutron Powder Diffraction Data Using GSAS  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Structure Analysis from Neutron Powder Diffraction Data Using GSAS Magnetic Structure Analysis from Neutron Powder Diffraction Data Using GSAS This set of web pages provides reference information from the Magnetic Structure Analysis from Neutron Powder Diffraction Data Using GSAS workshop presented at the 2006 American Conference on Neutron Scattering held in St. Charles, IL, June 18-22, 2006. Workshop Schedule: 9:00-9:05 am: Introduction (B.H. Toby) 9:05-9:50 am: History, Color symmetry & Shubnikov space groups (B. Chakoumous) Lecture notes: History and Color symmetry & Shubnikov space groups 9:50-10:20 am: Magnetic extinctions classes & common magnetic structure types (R.B. Von Dreele) Lecture Notes Break 10:50-11:45 am: Overview of representational analysis & FullProf implementation (L.C. Chapon) Lecture Notes and Accompanying files

3

Powder Diffraction  

NLE Websites -- All DOE Office Websites (Extended Search)

Powder Diffraction Powder Diffraction Ashfia Huq Spallation Neutron Source Oak Ridge National Laboratory 2 Managed by UT-Battelle for the U.S. Department of Energy Bragg's law W.H. Bragg (1862-1942) W.L. Bragg (1890-1971) *Zinc Blend (fcc not sc) *NaCl (not molecular) *Diamond (two overlapping fcc lattice) Shared 1915 Nobel Prize 3 Managed by UT-Battelle for the U.S. Department of Energy Where are the atoms? X-ray: (l : 10 -9 m - 10 -11 m) l[Å] = 12.398/E ph [keV] Source: * Lab diffractometers * Synchrotron Sources Neutron: (thermal l : 1-4Å) E n [meV] =81.89/ l 2 [Å] Source: * Reactors (fission) * Spallation Source We need wavelength (l) ~ Object size (for condensed matter that is Å) 4 Managed by UT-Battelle for the U.S. Department of Energy

4

Structural studies of magnesium nitride fluorides by powder neutron diffraction  

SciTech Connect

Samples of ternary nitride fluorides, Mg{sub 3}NF{sub 3} and Mg{sub 2}NF have been prepared by solid state reaction of Mg{sub 3}N{sub 2} and MgF{sub 2} at 1323-1423 K and investigated by powder X-ray and powder neutron diffraction techniques. Mg{sub 3}NF{sub 3} is cubic (space group: Pm3m) and has a structure related to rock-salt MgO, but with one cation site vacant. Mg{sub 2}NF is tetragonal (space group: I4{sub 1}/amd) and has an anti-LiFeO{sub 2} related structure. Both compounds are essentially ionic and form structures in which nitride and fluoride anions are crystallographically ordered. The nitride fluorides show temperature independent paramagnetic behaviour between 5 and 300 K. - Graphical abstract: Definitive structures of the ternary magnesium nitride fluorides Mg{sub 3}NF{sub 3} and the lower temperature polymorph of Mg{sub 2}NF have been determined from powder neutron diffraction data. The nitride halides are essentially ionic and exhibit weak temperature independent paramagnetic behaviour. Highlights: Black-Right-Pointing-Pointer Definitive structures of Mg{sub 3}NF{sub 3} and Mg{sub 2}NF were determined by neutron diffraction. Black-Right-Pointing-Pointer Nitride and fluoride anions are crystallographically ordered in both structures. Black-Right-Pointing-Pointer Both compounds exhibit weak, temperature independent paramagnetic behaviour. Black-Right-Pointing-Pointer The compounds are essentially ionic with ionicity increasing with F{sup -} content.

Brogan, Michael A. [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Hughes, Robert W. [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Smith, Ronald I. [ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Gregory, Duncan H., E-mail: Duncan.Gregory@glasgow.ac.uk [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2012-01-15T23:59:59.000Z

5

A six-axis robotic sample changer for high-throughput neutron powder diffraction and texture measurements  

Science Journals Connector (OSTI)

A new six-axis robotic sample changer for neutron powder diffraction experiments, including texture measurements, has enabled a novel set of experiments to be performed at the High-Pressure Preferred Orientation diffractometer at the Lujan Neutron Scattering Center.

Losko, A.S.

2014-11-18T23:59:59.000Z

6

Neutron Diffraction  

Science Journals Connector (OSTI)

22 February 1949 research-article Neutron Diffraction G. E. Bacon J. Thewlis The problem of neutron diffraction by crystals is treated by analogy...deals with a comparison between X-ray and neutron diffraction and it is shown that quantitatively...

1949-01-01T23:59:59.000Z

7

UNITED STATES ATOMIC ENERGY COMMISSION OAK RIDGE TENNESSEE THE DIFFRACTION OF NEUTRONS BY CRYSTALLINE POWDERS  

NLE Websites -- All DOE Office Websites (Extended Search)

MDDC 869 MDDC 869 UNITED STATES ATOMIC ENERGY COMMISSION OAK RIDGE TENNESSEE THE DIFFRACTION OF NEUTRONS BY CRYSTALLINE POWDERS by E. 0. Wollan C. G. Shull Clinton Laboratories Published for use within the Atomic Energy Commission. Inquiries for additional -copies and any questions regarding reproduction by recipients of this document may be referred to the Documents Distribution Subsection, Publication Section, Technical Information Branch, Atomic Energy Commission, P. 0. Box E, Oak Ridge, Tennessee. Inasmuch as a declassified document may differ materially from the original classified document by reason of deletions necessary to accomplish declassification, this copy does not constitute authority for declassification of classified copies of a similar document which may bear the same title and authors.

8

Static compression and H disorder in brucite, Mg(OH)2, to 11 GPa: a powder neutron diffraction study  

Science Journals Connector (OSTI)

Neutron diffraction data suitable for Rietveld refinements were collected on a powder sample of synthetic Mg(OH)2 by the Polaris time-of-flight spectrometer (ISIS spallation source, U.K.) at 10-4 7.8(3) and 10.9(...

M. Catti; G. Ferraris; S. Hull; A. Pavese

1995-04-01T23:59:59.000Z

9

POWDER: The Neutron Powder Diffractometer at HFIR | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Powder Diffractometer Neutron Powder Diffractometer Neutron Powder Diffractometer. Neutron Powder Diffractometer. The HB-2A diffractometer is a workhorse instrument used to conduct crystal structural and magnetic structural studies of powdered and ceramic samples, particularly as a function of intensive conditions (T, P, H, etc.). Powder diffraction data collected on this instrument are ideally suited for the Rietveld method. A full range of ancillary sample environments can be used, including cryofurnaces (4-800 K), furnaces (to 1800 K), cryostats (to 0.3 K), and cryomagnets (to 7 T). The Powder Diffractometer has a Debye-Scherrer geometry. The detector bank has 44 3He tubes, each with 6' Soller collimators. A germanium wafer-stack monochromator is vertically focusing and provides one of three principal

10

A powder neutron diffraction study of the magnetic structure of FeV{sub 2}S{sub 4}  

SciTech Connect

Variable-temperature powder neutron diffraction data demonstrate that FeV{sub 2}S{sub 4} undergoes a transition to a long-range magnetically ordered state at 135(7) K, in agreement with magnetic susceptibility data. High-resolution neutron diffraction data collected at 1.9 K reveal that magnetic ordering results in a doubling of the crystallographic unit-cell dimensions (I2/m a = 5.8303(2), b = 3.2761(1), c = 11.2398(4) {angstrom}, {beta} = 92.046(2){degree}) in the a and c directions and that the magnetic structure is described by a propagation vector of ({1/2}, 0, {1/2}). Cations in an ordered defect layer, 76% of which are Fe(II), possess an average ordered moment of 1.86(5) {mu}{sub B}, which is directed at an angle of 75{degree} to the layer. Cation-cation interactions reduce the average moment of cations in the MS{sub 2} unit to 0.17(4) {mu}{sub B}. The complex magnetic structure involves essentially collinear antiferromagnetic ordering between nearest-neighbor cations.

Powell, A.V.; Vaqueiro, P. [Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Chemistry] [Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Chemistry; Ritter, C. [Inst. Max von Laue-Paul Langevin, Grenoble (France)] [Inst. Max von Laue-Paul Langevin, Grenoble (France)

1999-05-01T23:59:59.000Z

11

Neutron Diffraction @ TOPAZ  

NLE Websites -- All DOE Office Websites (Extended Search)

Topaz Guide Bender Topaz Guide Bender Neutron Diffraction @ TOPAZ Workshop on Single Crystal Neutron Diffraction picture 2 September 29 - October 1, 2011 * Spallation Neutron Source * Oak Ridge National Laboratory * Oak Ridge TN, USA TOPAZ 2011 Home Contacts Agenda and Important Deadlines Registration and Payment filler Workshop summary and purpose A workshop on single crystal neutron diffraction will be held at the Spallation Neutron Source at the Oak Ridge National Laboratory (ORNL). It will present invited and contributed talks to showcase cutting edge science and examples where neutron diffraction can make significant contributions; and provide training in neutron structure analysis and sample screening for the preparation of instrument beam-time proposals. TOPAZ is a high resolution wavelength-resolved Laue diffractometer with a versatile sample environment. Commissioning user experiments have demonstrated successfully the instrument capability for structural study of a vitamin B12 derivative, ion distribution in Li-ion battery materials, order and disorder in shape memory intermetallics, magnetic phase transition in multiferroic single crystal and functional thin films. The workshop is directed towards experienced neutron diffraction users and new users alike and encourages members to highlight their research and interest in structure analysis and investigation. The workshop will give opportunity to bring your own single crystal and screen sample quality and scattering power on TOPAZ @ room temperature, to evaluate data collection time and quality for an anticipated experiment. Finally, an opportunity to compose a proposal for neutron beam time (http://neutrons.ornl.gov/users/proposals.shtml) with staff will be provided in the framework of the workshop. The workshop format is well suited for researchers to contribute by showcasing their research and bring their research group or graduate student, who would like to test a single crystal sample. User access training for the ORNL neutron scattering facility will be included. It will be valid for future experiments.

12

Neutron Diffraction Studies of Proteins  

Science Journals Connector (OSTI)

20 November 1980 research-article Neutron Diffraction Studies of Proteins G. A. Bentley S. A. Mason Neutrons interact differently with protein crystals...hydrogen or deuterium atoms diffract neutrons relatively more strongly, but in addition...

1980-01-01T23:59:59.000Z

13

Crystal structures and thermal expansion of -MgSO4 and -MgSO4 from 4.2 to 300 K by neutron powder diffraction  

Science Journals Connector (OSTI)

Powder neutron refinements of two MgSO4 polymorphs are presented, and their highly anisotropic thermal expansivity is analysed using a Debye model.

Fortes, A.D.

2007-07-13T23:59:59.000Z

14

SINGLE CRYSTAL NEUTRON DIFFRACTION.  

SciTech Connect

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.

KOETZLE,T.F.

2001-03-13T23:59:59.000Z

15

Neutron detectors comprising boron powder  

SciTech Connect

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

2013-05-21T23:59:59.000Z

16

LJournal of Alloys and Compounds 291 (1999) 94101 The simultaneous powder X-ray and neutron diffraction refinement of two  

E-Print Network (OSTI)

melting of metals in the The intermetallic ternary transition metal nitrides and presence of carbon]. These phases are of interest decomposition of transition metal tris­ethylenediamine to the solid state chemist diffraction refinement of two h-carbide type nitrides, Fe Mo N and Co Mo N, prepared by3 3 3 3 ammonolysis

zur Loye, Hans-Conrad

17

Neutron diffraction study of decaborane  

Science Journals Connector (OSTI)

Neutron diffraction study of decaborane ... The Molecular Structure of (PSH+)(nido-7,8-C2B9H12-) Determined by Neutron Diffraction (PS = Proton Sponge, 1,8-Bis(dimethylamino)naphthalene) ... The Molecular Structure of (PSH+)(nido-7,8-C2B9H12-) Determined by Neutron Diffraction (PS = Proton Sponge, 1,8-Bis(dimethylamino)naphthalene) ...

Armin Tippe; Walter C. Hamilton

1969-03-01T23:59:59.000Z

18

Magnetic Structure Determination from Neutron Diffraction Data  

NLE Websites -- All DOE Office Websites (Extended Search)

logo logo Magnetic Structure Determination from Neutron Diffraction Data September 17 - 20, 2012 logo Oak Ridge National Laboratory - Oak Ridge, Tennessee, USA About the Workshop Program Lecture Notes Useful Links Organizers Travel & Lodging Wireless Networking Photos filler About the Workshop molecule The Magnetic Structure Determination Workshop 2012 concluded on September 20. The aim of this workshop was to enhance the community studying magnetism in materials by learning from experts the essential theoretical foundations to magnetic representation analysis and work through real examples to gain experience in solving and refining magnetic structures from neutron powder and single crystal diffraction data. Invited speakers: Juan Rodríguez-Carvajal (ILL, Grenoble)

19

High-temperature neutron diffraction study of deuterated brucite  

Science Journals Connector (OSTI)

To study the structural behavior of brucite at high temperature, we conducted in situ neutron diffraction experiments of a deuterated brucite powder sample, Mg(OD)2, in the temperature range 313583K. The sample...

Hongwu Xu; Yusheng Zhao; Donald D. Hickmott

2013-11-01T23:59:59.000Z

20

Neutron diffraction by perfect crystals  

Science Journals Connector (OSTI)

The dynamical theory of neutron diffraction has been formulated to include the reflected waves from the boundaries of a crystal. This formulation allows a unified treatment of the neutron optical and diffraction phenomena in crystals. It is shown that the neutron propagation in the crystal is determined by two structure factors characterizing the lattice: the total structure factor and the structure factor of the neutron-spin-neutron-orbit interaction. Diffraction by a parallel crystal plate has been studied in considerable detail. It has been found that for a definite neutron-spin orientation, the diffracted and transmitted beams are modulated by six terms periodic in the thickness of the crystal. The period of the dominant term, in this Pendellsung fringe structure, has been calculated in several cases of experimental importance. If the glancing angle of incidence substantially exceeds the critical angle for total reflection, the results are identical with those obtained by a simple extension, to the neutron case, of the x-ray dynamical theory. The diffraction by a magnetized crystal has been examined in some detail and it is shown that measurement of the Pendellsung periods for the two neutron-spin orientations may be used to determine both the nuclear and magnetic neutron scattering amplitude.

C. Stassis and J. A. Oberteuffer

1974-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Neutron Diffraction Texture Analysis  

Science Journals Connector (OSTI)

...conducted at Chalk River (Canada), Geesthacht (Germany), LLB (France) and NIST...deformed limestone that was measured at Geesthacht with this method. It is also possible...with monochromatic neutrons at GKSS, Geesthacht. Equal area projection, linear contours...

Hans-Rudolf Wenk

22

Space Groups: A primer on topics significant for powder diffraction  

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Space Groups: A primer on topics significant for powder diffraction Presentation Goal Introduce symmetry concepts important for Rietveld analysis, particularly of inorganic...

23

Residual Stresses in Weldments by Neutron Diffraction  

E-Print Network (OSTI)

Residual Stresses in Weldments by Neutron Diffraction Shanmukha Rao M, Jon James, Shirley Northover :- The neutron diffraction is determined from Bragg's law. When neutron propagate through crystal sample, Coherent, Incoherent and Absorption Scattering phenomena take place Weld MaterialsPlate materials Stress

Bandara, Arosha

24

The P-V-T equation of state of D2O ice VI determined by neutron powder diffraction in the range 0 < P < 2.6 GPa and 120 < T < 330 K, and the isothermal equation of state of D2O ice VII from 2 to 7 GPa at room temperature  

Science Journals Connector (OSTI)

Ice VI is an important rock-forming mineral phase in icy planetary bodies; the pressure and temperature dependence of its density have been measured using powder neutron diffraction, throughout the high-pressure stability field, to obtain an accurate equation of state parameterization. These data are used to derive other thermodynamic quantities of use in planetary modelling.

Fortes, A.D.

2012-05-16T23:59:59.000Z

25

Neutron Diffraction of Ice in Hydrogels  

Science Journals Connector (OSTI)

Neutron Diffraction of Ice in Hydrogels ... (14, 15) Neutrons are also especially suited for studying D2O water in hydrogels because hydrogen atoms (H) on the polymer chains are not detectable. ...

Yurina Sekine; Tomoko Ikeda-Fukazawa; Mamoru Aizawa; Riki Kobayashi; Songxue Chi; Jaime A. Fernandez-Baca; Hiroki Yamauchi; Hiroshi Fukazawa

2014-08-26T23:59:59.000Z

26

Clifford G. Shull, Neutron Diffraction, Hydrogen Atoms, and Neutron  

Office of Scientific and Technical Information (OSTI)

Clifford Shull, Neutron Diffraction, and Neutron Scattering Clifford Shull, Neutron Diffraction, and Neutron Scattering Resources with Additional Information Clifford G. Shull was awarded the 1994 Nobel Prize in Physics "for the development of the neutron diffraction technique". 'Professor Shull's prize was awarded for his pioneering work in neutron scattering, a technique that reveals where atoms are within a material like ricocheting bullets reveal where obstacles are in the dark. Clifford Shull Photo Courtesy of Oak Ridge National Laboratory When a beam of neutrons is directed at a given material, the neutrons bounce off, or are scattered by, atoms in the sample being investigated. The neutrons' directions change, depending on the location of the atoms they hit, and a diffraction pattern of the atoms' positions can then be obtained.

27

High-pressure neutron diffraction study on HD isotope effects in brucite  

Science Journals Connector (OSTI)

A neutron powder diffraction study of hydrogenated and deuterated brucite was conducted at ambient temperature and at...a axis, parallel to the sheets of MgO octahedra, decrease only slightly with pressure with ...

Juske Horita; Antnio M. dos Santos

2010-12-01T23:59:59.000Z

28

Structure of high pressure Ca(OD){sub 2} II from powder neutron diffraction: Relationship to the ZrO{sub 2} and EuI{sub 2} structures  

SciTech Connect

The {open_quotes}unquenchable{close_quotes} high pressure form of Ca(OD){sub 2} [Ca(OH){sub 2}II] has been synthesized at 9 GPa and 400{degrees}C and recovered to ambient pressure at cryogenic temperatures. The structure was determined from powder neutron diffraction data using the Rietveld technique. The symmetry is monoclinic P2{sub 1}/c with a = 5.3979(4) {angstrom}, b = 6.0931(4) {angstrom}, c = 5.9852(4) {angstrom}, {beta} = 103.581(6), Z = 4 at 1 atm and 11 K. R{sub wp} = 2.8%, R{sub p} = 1.9%, reduced {chi}{sup 2} = 6.6. for 117 variables. The calcium and oxygen substructure is intermediate between that in {alpha}-PbO{sub 2} and that in fluorite; it was previously described as isostructural with baddeleyite (ZrO{sub 2}), but it is more accurately described as isostructural with EuI{sub 2}. This structure is distinguished by the presence of a 3{sup 6} anion met parallel to (100). Only one of the two kinds of D atoms in the structure shows appreciable hydrogen bonding to O, with a second neighbor D...O distance of 1.91 {angstrom}, and an O-D...O angle of 153.2{degrees}; the other D atom has 3 second-neighbor oxygens near 2.6 {angstrom} away.

Leinenweber, K.; Partin, D.E.; Schuelke, U. [Arziona State Univ., Tempe, AZ (United States)] [and others] [Arziona State Univ., Tempe, AZ (United States); and others

1997-09-01T23:59:59.000Z

29

Characterization of Li-ion Batteries using Neutron Diffraction...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Li-ion Batteries using Neutron Diffraction and Infrared Imaging Techniques Characterization of Li-ion Batteries using Neutron Diffraction and Infrared Imaging Techniques 2011 DOE...

30

Photon Sciences | Beamlines | XPD: X-ray Powder Diffraction  

NLE Websites -- All DOE Office Websites (Extended Search)

XPD: X-ray Powder Diffraction XPD: X-ray Powder Diffraction Poster | Fact Sheet | Preliminary Design Report Scientific Scope XPD is a tunable facility with the ability to collect diffraction data at high x-ray energies (40keV-80keV), offering rapid acquisition (millisecond) and high angular resolution capabilities on the same instrument. XPD addresses future scientific challenges in, for example, hydrogen storage, CO2 sequestration, advanced structural ceramics, catalysis, and materials processing. Such materials of high technological value often are complex, nanostructured and heterogeneous. The scientific grand challenge is to obtain robust and quantitative (micro)structural information, not only in the ground state at ambient conditions, but also in situ or in operando with varying temperature, pressure, magnetic/electric/stress

31

The Advanced Automation for Powder Diffraction toward Industrial Application  

SciTech Connect

A highly automated system for powder diffraction with synchrotron radiation was installed on the large Debye-Scherrer camera at the BL19B2 Engineering Science Research I beamline of SPring-8. Combined with a sample transfer and an automated centering system, we have succeeded in increasing the ratio of exposure time in the user beam time to 85%. The proposed system can be applied to a wide range of industrial uses.

Osaka, Keiichi; Matsumoto, Takuya; Miura, Keiko; Sato, Masugu; Hirosawa, Ichiro; Watanabe, Yoshio [Industrial Application Division, Japan Synchrotron Radiation Research Institute (JASRI/SPring8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

2010-06-23T23:59:59.000Z

32

The Advanced Automation for Powder Diffraction toward Industrial Application  

Science Journals Connector (OSTI)

A highly automated system for powder diffraction with synchrotron radiation was installed on the large Debye?Scherrer camera at the BL19B2 Engineering Science Research I beamline of SPring?8. Combined with a sample transfer and an automated centering system we have succeeded in increasing the ratio of exposure time in the user beam time to 85%. The proposed system can be applied to a wide range of industrial uses.

Keiichi Osaka; Takuya Matsumoto; Keiko Miura; Masugu Sato; Ichiro Hirosawa; Yoshio Watanabe

2010-01-01T23:59:59.000Z

33

In situ characterization of AIPO-14 using synchrotron powder diffraction.  

SciTech Connect

The separation of propane/propylene mixtures is an important yet difficult industrial process that can be accomplished by a pressure swing adsorption process using AlPO-14 as the adsorbent. Although the AlPO-14 structure has been studied with different techniques, the detailed structure under conditions of the adsorption process has not been clarified. We have used synchrotron x-ray powder diffraction and an in situ reactor system to obtain detailed structural information of AlPO-14 with the Rietvield method. Molecular modeling using the structural data allowed determination of the diffusion path of propylene in AlPO-14. The design of the in situ reactor system allows different chemicals to be loaded and the system to be heated and pressurized up to 90 psi with various gases or liquids. For this work, AlPO-14 powder was loaded into a 1 mm capillary tube and attached to the cell. Diffraction scans were collected during treatments in nitrogen, propane and propylene at various temperatures up to 300 C and various pressures up to 90 psig. A selected region of the x-ray diffraction patterns under different experimental conditions is shown in Fig.1. The diffraction patterns for AlPO-14 in nitrogen and propane are very similar, whereas the pattern in propylene changes considerably suggesting structure changes caused by adsorption of propylene into the pores.

Yang, N.; Greenlay, N.; Karapetrova, J.; Zschack, P.; Gatter, M.; Wilson, S.; Broach, R. W.; Experimental Facilities Division (APS); UOP

2006-01-01T23:59:59.000Z

34

DNA hydration studied by neutron fiber diffraction  

SciTech Connect

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.

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

1994-12-31T23:59:59.000Z

35

Powder Diffraction with Proteins Jon Wright, Irene Margiolaki, Andy Fitch and Yves Watier  

E-Print Network (OSTI)

Powder Diffraction with Proteins Jon Wright, Irene Margiolaki, Andy Fitch and Yves Watier #12 C 3Wright, Protein Powders #12;Wright, Protein Powders 4 Structure representations #12;Wright method to "solve" phase problem · What do we see in electron density maps? 6Wright, Protein Powders #12

Magee, Joseph W.

36

Real-space calculation of powder diffraction patterns on graphics processing units  

Science Journals Connector (OSTI)

This paper shows how the power of graphics processing units can be exploited to compute the powder diffraction pattern of nano-sized objects.

Gelisio, L.

2010-04-30T23:59:59.000Z

37

Neutron detectors comprising ultra-thin layers of boron powder  

SciTech Connect

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material having a thickness of from about 50 nm to about 250 nm and comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehul; Morris, Christopher

2013-07-23T23:59:59.000Z

38

Synchrotron and neutron powder diffraction study of phase transition in weberite-type Nd[subscript 3]NbO[subscript 7] and La[subscript 3]NbO[subscript 7  

SciTech Connect

La{sub 3}NbO{sub 7} and Nd{sub 3}NbO{sub 7} are insulating compounds that have an orthorhombic weberite-type crystal structure and undergo a phase transition at about 360 and 450 K, respectively. The nature of the phase transitions was investigated via heat capacity measurements, synchrotron X-ray and neutron diffraction experiments. It is here shown that above the phase transition temperature, the compounds possess a weberite-type structure described by space group Cmcm (No. 63). Below the phase transition, the high temperature phase transforms into a weberite-type structure with space group Pmcn (No. 62). The phase transformation primarily involves the off-center shifting of Nb{sup 5+} ions inside the NbO{sub 6} octahedra, combined with shifts of one third of the Ln{sup 3+} (Ln{sup 3+} = La{sup 3+} and Nd{sup 3+}) ions at the center of the LnO{sub 8} polyhedra towards off-center positions. The phase transition was also proven to have great impacts on the dielectric properties.

Cai, Lu; Nino, Juan C. (ORNL); (Florida)

2011-11-07T23:59:59.000Z

39

LANSCE | Lujan Center | Highlights | In situ neutron diffraction study of  

NLE Websites -- All DOE Office Websites (Extended Search)

In situ neutron diffraction study of CO clathrate hydrate In situ neutron diffraction study of CO clathrate hydrate The structure of a CO clathrate hydrate has been studied for the first time using high-P low-T neutron diffraction. Clathrate Rietveld analysis shows that lattice parameter a (SII cubic clathrate structure) increases with increasing temperature. CO molecules are positionally disordered and off-centered in both large and small cages. Each large cage is occupied by two CO molecules while each small cage is occupied by one CO. A representative neutron diffraction pattern of SII CO clathrate hydrate. Variation of lattice parameter a of CO SII clathrate hydrate as a function of temperature. A representative neutron diffraction pattern of SII CO clathrate hydrate. Variation of lattice parameter a of CO SII clathrate hydrate as a function of temperature.

40

Polarized neutron diffraction at a spallation source for magnetic studies  

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The first results from polarized neutron diffraction experiments on a time-of-flight instrument at a spallation source are reported. Higher neutron beam flux and efficient spin polarization at the neutron beamline enable in situ studies of phenomena contributing to field-induced magnetization in materials including magnetic shape memory alloys.

Pramanick, A.

2012-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

RisR1440(EN) Neutron diffraction stud-  

E-Print Network (OSTI)

. C. Canfield, Neutron scattering studies of the flux line lattice and magnetic ordering in TmNi2B2CRisø­R­1440(EN) Neutron diffraction stud- ies of magnetic ordering in superconducting ErNi2B2C Faculty of Science, University of Copenhagen January 2004 #12;Abstract This thesis describes neutron

42

The hybrid big bang-big crunch method for solving crystal structure from powder diffraction data  

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The big bang-big crunch optimization method has been revised, combined with the simulated annealing technique and implemented in the latest version of the EXPO program for solving crystal structure from powder diffraction data.

Altomare, A.

2013-05-15T23:59:59.000Z

43

Temperature and TimeResolved XRay Powder Diffraction X14A EERE sponsored PRT beamline  

E-Print Network (OSTI)

Temperature and TimeResolved XRay Powder Diffraction X14A EERE sponsored PRT beamline Objective, in ambience or with gas flow Capabilities: X14A, EERE-sponsored PRT beamline · High photon flux: typically 9x

Ohta, Shigemi

44

Synchrotron and neutron powder diffraction study of phase transition in weberite-type Nd{sub 3}NbO{sub 7} and La{sub 3}NbO{sub 7}  

SciTech Connect

La{sub 3}NbO{sub 7} and Nd{sub 3}NbO{sub 7} are insulating compounds that have an orthorhombic weberite-type crystal structure and undergo a phase transition at about 360 and 450 K, respectively. The nature of the phase transitions was investigated via heat capacity measurements, synchrotron X-ray and neutron diffraction experiments. It is here shown that above the phase transition temperature, the compounds possess a weberite-type structure described by space group Cmcm (No. 63). Below the phase transition, the high temperature phase transforms into a weberite-type structure with space group Pmcn (No. 62). The phase transformation primarily involves the off-center shifting of Nb{sup 5+} ions inside the NbO{sub 6} octahedra, combined with shifts of one third of the Ln{sup 3+} (Ln{sup 3+}=La{sup 3+} and Nd{sup 3+}) ions at the center of the LnO{sub 8} polyhedra towards off-center positions. The phase transition was also proven to have great impacts on the dielectric properties. - Graphical abstract: The phase transition of La{sub 3}NbO{sub 7} and Nd{sub 3}NbO{sub 7} upon cooling primarily involves the off-center shifting of Nb{sup 5+} ions inside the NbO{sub 6} octahedra, combined with shifts of one third of the Ln{sup 3+} (Ln{sup 3+}=La{sup 3+} and Nd{sup 3+}) ions at the center of the LnO{sub 8} polyhedra towards off-center positions. Above the phase transition temperature, Ln{sup 3+} and Nb{sup 5+} sit at a position with mirror symmetry and 2-fold axis. Below the phase transition temperature, Ln{sup 3+} and Nb{sup 5+} shift away from the 2-fold axis but still in the mirror plane. Highlights: > La{sub 3}NbO{sub 7} and Nd{sub 3}NbO{sub 7} exhibit a phase transition at 360 and 450 K, respectively. > The phase transformation primarily involves the off-center shifting of Nb{sup 5+} and Ln{sup 3+}. > The off-center ionic displacement decreases with increasing temperature. > Dielectric properties are greatly related to the off-center displacement.

Cai Lu, E-mail: cail@ornl.gov [Spallation Neutron Source, Oak Ridge National Laboratory, PO Box 2008 MS6454, Oak Ridge, TN 37831 (United States); Nino, Juan C. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States)

2011-08-15T23:59:59.000Z

45

RECENT CRYSTAL STRUCTURE DETERMINATIONS BY NEUTRON DIFFRACTION AT OAK RIDGE  

E-Print Network (OSTI)

469. RECENT CRYSTAL STRUCTURE DETERMINATIONS BY NEUTRON DIFFRACTION AT OAK RIDGE By GEORGE M. BROWN and HENRI A. LEVY, Chemistry Division Oak Ridge National Laboratory (1), Oak Ridge, Tennessee, U. S. A ont été relevées grace au diffractomètre à neutrons d'Oak Ridge position- nant automatiquement les

Paris-Sud XI, Université de

46

Supplementary Figure 1| Neutron diffraction data at 86 % relative humidity. a) Schematic representation of neutron diffraction geometry for -2 scans. Diffraction data are obtained  

E-Print Network (OSTI)

distributions of lipid and protein under varying levels of hydration. Predicted neutron scattering profiles as number density profiles weighted by the neutron scattering lengths of individual atoms, then symmetrizedSupplementary Figure 1| Neutron diffraction data at 86 % relative humidity. a) Schematic

White, Stephen

47

Sub-Surface Residual Stress Measurements by Means of Neutron Diffraction: Aluminum, Steel, and Depleted Uranium  

Science Journals Connector (OSTI)

Neutron diffraction closely parallels x-ray diffraction in methodology and analytical formalism. However, in the normal diffraction range (? ~ 1 ) neutrons are nondestructive and are generally about a thousand t...

H. J. Prask; C. S. Choi

1986-01-01T23:59:59.000Z

48

Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings  

SciTech Connect

A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.

Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R

2009-01-01T23:59:59.000Z

49

Oxides: neutron and synchrotron X-ray diffraction studies  

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......cells. Their thermal stability and high proton conductivity are particu- 15000 15500 16000 16500 17000 Time-of-flight, usec Fig. 6 Neutron diffraction pattern of the high temperature protonic conductor Ba3Ca! uNb].82O9-5 with and without D2O......

Izabela M. Sosnowska; Makoto Shiojiri

1999-01-01T23:59:59.000Z

50

Neutron diffraction study of the contribution of grain contacts to nonlinear stress-strain behavior  

E-Print Network (OSTI)

Neutron diffraction study of the contribution of grain contacts to nonlinear stress-strain behavior performed simultaneous neutron diffraction and quasi-static loading experiments on a selection of rocks to experimentally isolate the response of these contact regions. Neutron diffraction measures strain in the lattice

51

NEUTRON DIFFRACTION ANALYSIS OF CYTOCHROME b5 RECONSTITUTED IN DEUTERATED LIPID MULTILAYERS  

E-Print Network (OSTI)

NEUTRON DIFFRACTION ANALYSIS OF CYTOCHROME b5 RECONSTITUTED IN DEUTERATED LIPID MULTILAYERS E. P centrosymmetric pairs of asymmetric lipid-protein bilayers. Lamellar neutron diffraction data were collected. A neutron diffraction analysis ofcytochrome b5, incorporated into ordered lipid multilayers, promised

52

Neutron Powder Diffraction and Molecular Simulation Study of...  

NLE Websites -- All DOE Office Websites (Extended Search)

leading to the rotation of the B-N bond parallel to the c-axis. The structural phase transition at 225 K is marked by dramatic change in the dynamics of both the amine and borane...

53

Structures of FeII spin-crossover complexes from synchrotron powder-diffraction data  

Science Journals Connector (OSTI)

Using synchrotron powder-diffraction data and direct-space search techniques, crystal structures have been obtained at room temperature and 90 K for the compounds [Fe(teeX)6](BF4)2 (teeX is haloethyltetrazole, and X = I and Br), which both show a gradual, complete high-spin-to-low-spin transition according to molar magnetic susceptibility and 57Fe Mssbauer spectroscopy.

Dova, E.

2004-09-15T23:59:59.000Z

54

Structure of K-doped polyacetylene and its variations with annealing, studied by neutron diffraction  

E-Print Network (OSTI)

complementary information to X-ray diffraction can be obtained with neutrons. In addition, neutron scatteringL-379 Structure of K-doped polyacetylene and its variations with annealing, studied by neutron~u le 9 janvier 1985, accepte le 21 fevrier 1985) Résumé. 2014 On a étudié par diffraction de neutrons

Boyer, Edmond

55

High Throughput Software for Powder Diffraction and its Application to Heterogeneous Catalysis  

E-Print Network (OSTI)

In this thesis we investigate high throughput computational methods for processing large quantities of data collected from synchrotrons and their application to spectral analysis of powder diffraction data. We also present the main product of this PhD programme, specifically a software called 'EasyDD' developed by the author. This software was created to meet the increasing demand on data processing and analysis capabilities as required by modern detectors which produce huge quantities of data. Modern detectors coupled with the high intensity X-ray sources available at synchrotrons have led to the situation where datasets can be collected in ever shorter time scales and in ever larger numbers. Such large volumes of datasets pose a data processing bottleneck which augments with current and future instrument development. EasyDD has achieved its objectives and made significant contributions to scientific research. It can also be used as a model for more mature attempts in the future. EasyDD is currently in use by a number of researchers in a number of academic and research institutions to process high-energy diffraction data. These include data collected by different techniques such as Energy Dispersive Diffraction, Angle Dispersive Diffraction and Computer Aided Tomography. EasyDD has already been used in a number of published studies, and is currently in use by the High Energy X-Ray Imaging Technology project. The software was also used by the author to process and analyse datasets collected from synchrotron radiation facilities. In this regard, the thesis presents novel scientific research involving the use of EasyDD to handle large diffraction datasets in the study of alumina-supported metal oxide catalyst bodies. These data were collected using Tomographic Energy Dispersive Diffraction Imaging and Computer Aided Tomography techniques.

Taha Sochi

2010-12-20T23:59:59.000Z

56

Attenuation corrections for X-ray and neutron fibre diffraction studies  

Science Journals Connector (OSTI)

The form of the transmission factor for sample geometries encountered in X-ray and neutron fibre diffraction studies is considered.

Langan, P.

1995-02-01T23:59:59.000Z

57

Powder diffraction studies on proteins : An overview of data collection approaches.  

SciTech Connect

Following the seminal work of Von Dreele, high quality powder X-ray diffraction studies on proteins are being established as a valuable complementary technique to single-crystal measurements. Several studies using a variety of experiments approaches have been reported in the literature, including high-resolution studies employing parallel beam geometry and high intensity measurements using position sensitive detectors. The choice of the optimum instrumental configuration depends on a number of competing factors such as the amount of sample available, its radiation sensitivity, and the quality of the data required for data analysis, e.g. angular resolution, the extent of the data in d-spacing, or the number of patterns required to explore the protein's behaviour at different temperatures, or under different crystallisation conditions, etc. Here we discuss several advantages and disadvantages of different data collection methods followed for selected examples of small proteins.

Margiolaki, I.; Wright, J. P.; Fitch, A. N.; Fox, G. C.; Labrador, A.; Von Dreele, R. B.; Miura, K.; Gozzo, F.; Schiltz, M.; Besnard, C.; Camus, F.; Pattison, P.; Beckers, D.; Degen, T.; X-Ray Science Division; European Synchrotron Radiation Facility; Japan Synchrotron Radiation Research Inst.; Swiss Light Source; Ecole Polytechnique Federale de Lausanne; PANalytical

2007-01-01T23:59:59.000Z

58

Neutron diffraction measurements of residual stresses in welds fabricated from highly anisotropic materials  

NLE Websites -- All DOE Office Websites (Extended Search)

neutron diffraction to neutron diffraction to engineering problems T.M. Holden Northern Stress Technologies Deep River, Ontario, Canada Oak Ridge National Laboratory, 13 nd June 2011 Reference material * "Introduction to the characterization of residual stress by neutron diffraction". M.T. Hutchings, P.J. Withers, T.M. Holden and T. Lorentzen, (Taylor and Francis: Boca Raton) 2005 * "Introduction to diffraction in Materials Science and Engineering", A.D. Krawitz (John Wiley and Sons ,Inc.: New York) 2001 * "Non-destructive testing-Standard Test Method for

59

RECENT MAGNETIC STRUCTURE STUDIES BY NEUTRON DIFFRACTION(1) By C. G. SHULL,  

E-Print Network (OSTI)

classification by neutron scattering include the determination of the magnitude and quality of an atom of this moment as represented in the form factor for neutron scattering. Within the second classification169 RECENT MAGNETIC STRUCTURE STUDIES BY NEUTRON DIFFRACTION(1) By C. G. SHULL, Massachusetts

Boyer, Edmond

60

Neutron and X-ray diffraction and empirical potential structure refinement modelling of magnesium stabilised amorphous calcium  

E-Print Network (OSTI)

Neutron and X-ray diffraction and empirical potential structure refinement modelling of magnesium online xxxx Keywords: Amorphous calcium carbonate; EPSR modelling; Neutron diffraction; X-ray diffraction Amorphous calcium carbonate (ACC) plays a key role in biomineralisation processes in sea organisms. Neutron

Benning, Liane G.

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Capabilities of the POWDER Instrument | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Capabilities of the POWDER Instrument Capabilities of the POWDER Instrument The scientific areas that may benefit from using the HB-2A instrument are condensed matter physics, chemistry, geology, and material science. Due to its versatility, this instrument can be employed for a large variety of experiments, but it is particularly adapted for determining crystal structures with relatively large unit cells (dmax ≈ 28 Å), as well as complex magnetic structures. Furthermore, studies of phase transitions, thermal expansion, quantitative analysis, and ab-initio structure solution from powder data can be undertaken. A full range of ancillary sample environments can be used to provide a complete control of thermodynamic variables such as temperature, magnetic field, and pressure. The following examples highlight some of the basic features and

62

Collecting and Processing Neutron Fibre Diffraction Data from a Single-Crystal Diffractometer  

Science Journals Connector (OSTI)

An optimum strategy for collecting fibre diffraction data from a neutron single-crystal diffractometer is proposed. Methods for processing data collected using this strategy are described and illustrated by studies on cellulose.

Langan, P.

1996-08-01T23:59:59.000Z

63

Boron-10 Prompt Gamma Analysis Using a Diffracted Neutron Beam  

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A prompt gamma neutron activation analysis (PGNAA) facility has been built at the 5 MW MITR-II Research Reactor to support our ongoing boron neutron capture therapy (NCT) program. This facility is used to dete...

R. Rogus; O. K. Harling; I. Olmez

1992-01-01T23:59:59.000Z

64

Ultra-low-temperature neutron diffraction. Final report, July 1, 1983-June 30, 1985. Final report  

SciTech Connect

An ultra-low-temperature neutron diffraction facility has been constructed at Argonne National Laboratory. The initial and primary purpose of this facility is to study nuclear magnetic ordering phenomenon. Magnetic structure information is commonly recognized as being fundamental to the progress in theoretical and experimental efforts in the field of magnetism. We have initiated study of the nuclear spin in solid /sup 3/He and in metals. In /sup 3/He the nuclear spins order at 1.1 mK. Structure information for neutron diffraction would contribute significantly to this problem of nuclear magnetism. Despite substantial experimental difficulties, careful evaluation suggests that examination of the nuclear structure in this unique quantum crystal is indeed feasible by neutron diffraction. Substantial progress has been made in growing single crystals of /sup 3/He and establishing its temperature in the presence of a neutron flux. We have also initiated investigation of nuclear ordering in copper and PrCu/sub 6/.

Halperin, W.P.; Ketterson, J.B.

1985-07-01T23:59:59.000Z

65

Neutron Laue diffraction studies of coenzyme cob(II)alamin  

Science Journals Connector (OSTI)

A novel single-crystal neutron diffractometer utilizing a polychromatic neutron beam reduces data-collection times by about one order of magnitude. It is specifically suited for applications involving crystals of biological macromolecules. It was used to determine the arrangement of solvent molecules in the crystal structure of coenzyme B12r.

Langan, P.

1999-01-01T23:59:59.000Z

66

In-Situ Neutron Diffraction Studies of Complex Hydrogen Storage Materials  

SciTech Connect

The thrust of this project was to investigate the structures of important materials with potential application to hydrogen storage, in an effort to meet the DOE goals for 2010 and 2015, namely 9% (wt) and 15% (wt) respectively. Unfortunately, no material has been found, despite the efforts of many laboratories, including our own, that achieves these goals in a reversible complex hydride such as ammonia borane (NH{sub 4}BH{sub 4}), and other ammonia based compounds, or with light hydrides such as LiBH{sub 4}, due either to their irreversibility or to the high decomposition temperatures and residual simple hydrides such as LiH from the decomposition of the last named compound. Nevertheless, several important technical goals have been accomplished that could be valuable to other DOE programs and would be available for collaborative research. These include the development of a high quality glove box with controlled (low) oxygen and water content, which we continue to employ for the synthesis of potential new materials (unfunded research) and the development of a high quality neutron diffraction furnace with controlled gas environment for studies of hydrogen uptake and loss as well as for studies with other gasses. This furnace was initially constructed with an alumina (Al{sub 2}O{sub 3}) center tube to contain the sample and the flowing gas. The heaters are located in the vacuum space outside the tube and it was found that, for the low temperatures required for the study of hydrogen storage materials, the heat transfer was too poor to allow good control. At temperatures in excess of about 400C (and up to more than 1200C) the heat transfer and control are excellent. For the lower temperatures, however, the center tube was replaced by stainless steel and temperature control to 1C became possible. The paired heaters, above and below the neutron beam window allowed control of the temperature gradient to a similar precision. The high temperature capability of the furnace should make it a very valuable resource for the study of oxides being considered for application to solid oxide fuel cells (SOFCs), in that materials can be studied at potential operating temperatures in both reducing and oxidizing environments to determine their stoichiometry, and lattice parameters. Our research, which was predicated, in part, on the use of hydrogenous samples (as opposed to deuteration), demonstrated that such studies are feasible and can yield high quality, refinable data. The precision of the refined hydrogen positions appears to be more than adequate for theory calculations (molecular modeling-thermodynamics) and the uncertainty is certainly less than that achieved by attempting to extrapolate the hydrogen positions from refined deuterium positions. In fact the 2008 annual report from the Institute Laue Langevin (ILL), the world's premier neutron scattering laboratory, highlights: Another trend is the increasing interest in hydrogen. This defies the widespread assumption that neutron diffraction experiments need to be done at deuterated samples. In situ experiments on phase transitions involving hydrogen and in particular on the real time behaviour of hydrogen-storage systems increase in number and scope. Our work in this area predates the ILL efforts be several years. Unfortunately, the productivity of our program was significantly curtailed by the unavailability of the MURR powder diffractometer for almost all of the second years of the project. The diffractometer was disassembled to allow partial extraction of the beam tube and replacement of the graphite element that is penetrated by the beam tube. Re-commissioning of the instrument was substantially delayed by errors of the MURR engineering staff, which failed to properly reinstall the sapphire filter that conditions the beam prior to the neutron monochromator, and reduces the radiological background to acceptable levels.

Yelon, William B.

2013-05-13T23:59:59.000Z

67

Neutron diffraction studies on the Heusler alloy Ni{sub 50}Mn{sub 37}Sb{sub 13}  

SciTech Connect

The evolution of martensitic to austenitic transformation in Ni{sub 50}Mn{sub 37}Sb{sub 13} has been studied usingtemperature dependent neutron diffraction, thermal property, and magnetization studies. Differential scanning calorimetric studies reveal a martensitic transformation T{sub M} around 291 K. The magnetization data yield a ferromagnetic ordering temperature of 329 K in the austenitic phase and 230 K in the martensitic phase. The analysis of the powder neutron diffraction data in the temperature range of 325-12 K indicates a structural transition from a high temperature cubic L2{sub 1} type structure to an orthorhombic structure. At 270 K, both cubic and orthorhombic phases coexist. Anisotropic unit cell changes are observed at the martensitic transformation: The unit cell expands by about 1.5% along the a axis, by about 2.5% along the c axis, and compresses by about 4.28% along the b axis. Both cubic and orthorhombic phases show commensurate collinear ferromagnetic ordering with a magnetic moment of {approx}3.67 {mu}{sub B}/Mn in Mn (2a and 2f) sites.

Rama Rao, N. V.; Chelvane, J. Arout; Chandrasekaran, V. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Morozkin, A. V. [Department of Chemistry, Moscow Lomonosov State University, Moscow 119992 (Russian Federation); Lamsal, J. [Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Yelon, W. B. [Materials Research Center and Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States); Nirmala, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Suresh, K. G. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400 076 (India); Malik, S. K. [International Institute of Physics (IIP)-UFRN, Natal, 59072-970 (Brazil)

2011-04-01T23:59:59.000Z

68

Crystal structure of brucite-type cobalt hydroxide ?-Co{O(H,D)}2 neutron diffraction, IR and Raman spectroscopy  

Science Journals Connector (OSTI)

The crystal structure of brucite-type Co(OD)2 (space group P3?ml, Z = 1, a = 317.79(4) pm and c = 464.2(1) pm, RI = 5.89%) has been refined by neutron powder diffraction studies on the basis of 671 observations and 44 reflections. Infrared and Raman spectra of cobalt hydroxide at different degrees of deuteration are presented and assigned to the internal, librational and translational modes. The D?O distance of 252.8 pm and the wavenumbers of the OH and OD stretching modes (3604 and 2665 cm?1, 90 K, mean values of the unit-cell group modes) do not exclude the formation of weak trifurcated hydrogen bonds. The librational and translational vibrations of Eu species are strongly coupled as shown by the respective isotopic shifts. A reassignment of the IR-allowed librations and lattice vibrations of transition metal brucite-type hydroxides is given.

Ch. Mockenhaupt; Th. Zeiske; H.D. Lutz

1998-01-01T23:59:59.000Z

69

Irradiation creep of nano-powder sintered silicon carbide at low neutron fluences  

SciTech Connect

The irradiation creep behavior of nano-powder sintered silicon carbide was investigated using the bend stress relaxation method under neutron irradiation up to 1.9 dpa. The creep deformation was observed at all temperatures ranging from 380 to 1180 C mainly from the irradiation creep but with the increasing contributions from the thermal creep at higher temperatures. Microstructural observation and data analysis were performed.

Koyanagi, Takaaki [ORNL; Shimoda, Kazuya [Kyoto University, Japan; Kondo, Sosuke [Kyoto University, Japan; Hinoki, Tatsuya [Kyoto University, Japan; Ozawa, Kazumi [ORNL; Katoh, Yutai [ORNL

2014-01-01T23:59:59.000Z

70

Neutron diffraction study of the formation of ordered antiphase domains in cubic titanium carbide TiC{sub 0.60}  

SciTech Connect

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.

Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S. [Academy of Sciences of Uzbekistan, Institute of Nuclear Physics (Uzbekistan)

2013-05-15T23:59:59.000Z

71

A preliminary time-of-flight neutron diffraction study on amicyanin from paracoccus denitrificans.  

SciTech Connect

Crystals of the blue copper protein amicyanin suitable for neutron diffraction were grown by the sitting-drop method, followed by repeated macroseeding using solutions prepared with D{sub 2}O. Although the crystal sizes were the same, crystals grown using solutions made up in H{sub 2}O in the initial stages of macroseeding and solutions with D{sub 2}O in later stages did not diffract neutrons well. However, when the protein was initially exchanged with buffered D{sub 2}O and then crystallized and also macroseeded using solutions made up in D{sub 2}O throughout, the crystals diffracted neutrons to high resolution. One of those crystals was used to collect a data set to a resolution of 1.9 {angstrom}.

Sukumar, N.; Langan, P.; Mathews, F. S.; Jones, L. H.; Thiyagarajan, P.; Schoenborn, B. P.; Davidson, V. L.; ASO; IPNS

2005-05-01T23:59:59.000Z

72

in-situ chemistry mapping of hydrogen storage materials by neutron diffraction  

SciTech Connect

Neutron diffraction was used to nondestructively study the microstructures for two hydrogen storage media systems. In the first case, sodium alanate based hydrogen storage is a vehicle-scale candidate system developed by Sandia/GM. Neutron scattering was used to determine the distribution of phases in the storage media at different hydrogen loading levels, to help understand the absorption/desorption of hydrogen in large-scale systems. This study also included a 3D neutron tomographic study of the microstructure. In the second case, tin-doped lanthanum nickel alloys have been studied at JPL for space-based applications, for which the gradual degradation of the material due to segregation and disproportionation of phases is a known problem. A regenerative process developed to restore the storage properties of these alloys was studied, using in-situ neutron diffraction to relate the microstructure to the thermodynamic simulations.

Payzant, E Andrew [ORNL] [ORNL; Bowman Jr, Robert C [ORNL] [ORNL; Johnson, Terry A [Sandia National Laboratories (SNL)] [Sandia National Laboratories (SNL); Jorgensen, Scott W [GM R& D and Planning, Warren, Michigan] [GM R& D and Planning, Warren, Michigan

2013-01-01T23:59:59.000Z

73

Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers.  

SciTech Connect

The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar{reg_sign} or Twaron{reg_sign}.

Parrot, I. M. [Institut Laue-Langevin (ILL); Urban, Volker S [ORNL; Gardner, K. H. [DuPont Experimental Station; Forsyth, V. T. [Institut Laue Langevin and Keele University

2005-04-01T23:59:59.000Z

74

Processing of Neutron Diffraction Data for Strain Measurement in Geological Materials  

SciTech Connect

: Conventional rock mechanics testing techniques typically involve the loading of samples and measurement of displacements or strains on the outer boundary of the specimen surface. Neutron diffraction based strain measurement techniques represent a unique and powerful tool for measuring the strain within geological materials under load. The structural variability and non-uniform crystallinity of geological materials, however, create many complexities in the intensity patterns that must be analyzed to quantify strains within the material. The attenuating and scattering properties of the pressure cell housing the sample further add difficulties to the data analysis. This paper describes the methods and processes used to process neutron scattering data for strain measurement in geological materials. It is intended to provide a primer for those in the rock mechanics community that are interested in utilizing this technique along with additional discussion of neutron diffraction experimental factors that may affect data quality.

Polsky, Yarom [ORNL] [ORNL; An, Ke [ORNL] [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Bingham, Philip R [ORNL] [ORNL; Carmichael, Justin R [ORNL] [ORNL; Dessieux Jr, Luc Lucius [ORNL] [ORNL

2014-01-01T23:59:59.000Z

75

Quantitative determination of mineral composition by powder x-ray diffraction  

DOE Patents (OSTI)

An external standard intensity ratio method is used for quantitatively determining mineralogic compositions of samples by x-ray diffraction. The method uses ratios of x-ray intensity peaks from a single run. Constants are previously determined for each mineral which is to be quantitatively measured. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of a reference mineral contained in the sample are used to calculate sample composition.

Pawloski, G.A.

1984-08-10T23:59:59.000Z

76

Revealing cyclic hardening mechanism of a TRIP steel by real-time in situ neutron diffraction  

SciTech Connect

Real-time in situ neutron diffraction was performed on a transformation-induced plasticity (TRIP) steel under cyclic loading at room temperature. By Rietveld refinement and single peak analysis, the volume fraction and average stress estimates as well as dislocation density of individual phases (austenite and martensite phase) were derived. The results reveal that the volume fraction of martensite phase, instead of individual phase strengthening, should be accounted for the remarkable secondary cyclic hardening.

Yu, Dunji [ORNL; An, Ke [ORNL; Chen, Yan [ORNL; Chen, Xu [Tianjin UNiversity, China

2014-01-01T23:59:59.000Z

77

Anharmonicity and isomorphic phase transition: a multi-temperature X-ray single-crystal and powder diffraction study of 1-(2'-aminophenyl)-2-methyl-4-nitroimidazole  

Science Journals Connector (OSTI)

Multi-temperature single-crystal and powder diffraction experiments on 1-(2'-aminophenyl)-2-methyl-4-nitroimidazole show that this crystal undergoes an isomorphic phase transition with the coexistence of two phase domains over a wide temperature range. The anharmonic approach was the only way to model the resulting disorder.

Poulain, A.

2014-02-28T23:59:59.000Z

78

Crystal Structure and Hydrogen-Bonding System in Cellulose I? from Synchrotron X-ray and Neutron Fiber Diffraction  

Science Journals Connector (OSTI)

The crystal and molecular structure together with the hydrogen-bonding system in cellulose I? has been determined using synchrotron and neutron diffraction data recorded from oriented fibrous samples prepared by aligning cellulose microcrystals from ...?

Yoshiharu Nishiyama; Paul Langan; Henri Chanzy

2002-07-10T23:59:59.000Z

79

Structure determination of Ag-Ge-S glasses using neutron diffraction  

Science Journals Connector (OSTI)

The structure of the superionic glass system (Ag2S)x(GeS2)1-x, for three compositions x=0.3, 0.4, 0.5, has been studied using neutron diffraction, and isotopic-substitution neutron-diffraction experiments have been performed on three silver isotope-substituted (107Ag,natAg,109Ag) samples of the composition (Ag2S)0.5(GeS2)0.5. The average short-range orderings of Ge-S, Ag-S, and Ge-Ag correlations were identified in the radial distribution functions for the isotopically substituted system of (Ag2S)0.5(GeS2)0.5. From the first and second differences in the three sets of isotopic-substitution neutron-diffraction data, the other three partial correlations (Ag-Ag, Ge-Ge, and S-S), were also identified. By examining unusually broad peaks in the Ag-Ag correlation function, it was concluded that the Ag-Ag distribution was rather homogeneous. We were also able to obtain further information by combining the first and second difference analyses, resulting in a structural model of a slightly elongated GeS4 tetrahedron with the local environment of Ag+ ions being threefold coordination by nonbridging sulphur ions. The medium-range order of the host framework was found to be a chainlike structure of linked corner-sharing GeS4 tetrahedra. Substantial changes in the first and second peaks in the distinct scattering functions i(Q) were found with composition and also with isotopic substitution. It was possible to explain the trends in the changes of the heights of these peaks in the structure factor by applying the void model for the first sharp diffraction peak. 1996 The American Physical Society.

J. H. Lee; A. P. Owens; A. Pradel; A. C. Hannon; M. Ribes; S. R. Elliott

1996-08-01T23:59:59.000Z

80

Time-of-flight neutron diffraction study of bovine [gamma]-chymotrypsin at the Protein Crystallography Station  

SciTech Connect

The overarching goal of this research project is to determine, for a subset of proteins, exact hydrogen positions using neutron diffraction, thereby improving H-atom placement in proteins so that they may be better used in various computational methods that are critically dependent upon said placement. In order to be considered applicable for neutron diffraction studies, the protein of choice must be amenable to ultrahigh-resolution X-ray crystallography, be able to form large crystals (1 mm{sup 3} or greater) and have a modestly sized unit cell (no dimension longer than 100 {angstrom}). As such, {gamma}-chymotrypsin is a perfect candidate for neutron diffraction. To understand and probe the role of specific active-site residues and hydrogen-bonding patterns in {gamma}-chymotrypsin, neutron diffraction studies were initiated at the Protein Crystallography Station (PCS) at Los Alamos Neutron Science Center (LANSCE). A large single crystal was subjected to H/D exchange prior to data collection. Time-of-flight neutron diffraction data were collected to 2.0 {angstrom} resolution at the PCS with 85% completeness. Here, the first time-of-flight neutron data collection from {gamma}-chymotrypsin is reported.

Lazar, Louis M.; Fisher, S. Zoe; Moulin, Aaron G.; Kovalevsky, Andrey; Novak, Walter R.P.; Langan, Paul; Petsko, Gregory A.; Ringe, Dagmar (Brandeis); (LANL)

2012-02-06T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Xray and neutron diffraction studies and MD simulation of atomic configurations in polyamorphic Y2O3-Al2O3 systems  

Science Journals Connector (OSTI)

...McMillan and David C. Clary X-ray and neutron diffraction studies and MD simulation...new results of structural studies using neutron and high-energy X-ray diffraction...pair-correlation functions obtained from X-ray and neutron scattering data. Unexpectedly large density...

2005-01-01T23:59:59.000Z

82

Neutron powder diffraction of metal-organic frameworks for hydrogen storage  

Science Journals Connector (OSTI)

We review recent structural studies that we have undertaken aimed at elucidating the fundamental properties of metal-organic framework materials and their interactions with hydrogen. We have shown that exposin...

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

2008-10-01T23:59:59.000Z

83

Neutron diffraction studies and magnetism in Ti doped SrFeO{sub 3??} systems  

SciTech Connect

The magnetic ground state of single phase tetragonal crystal structure with I4/mmm space group SrFe{sub 1?x}Ti{sub x}O{sub 3??} (x?=?0.2 and 0.3) is investigated from 2?K to 300?K. Strong irreversibility is observed in zero-field-cooled (ZFC) and field-cooled DC magnetization curves. Arrott plots show the absence of spontaneous magnetization (M{sub S}) down to 2?K, ruling out the possibility of long range ferromagnetic order. Neutron diffraction measurements carried out at H?=?0, 7?T (field cooled) at several temperatures above and below the T* (temperature at which M{sub ZFC}(T) is maximum) do not show any additional peaks and also no difference in intensity rules out, both the long range antiferromagnetic and ferromagnetic orders. Hence, the combined study of dc magnetization and neutron diffraction results reveals cluster spin glass behavior in SrFe{sub 1?x}Ti{sub x}O{sub 3??} (x?=?0.2 and 0.3)

Sendil Kumar, A.; Srinath, S., E-mail: srinath@uohyd.ac.in [School of Physics, University of Hyderabad, Hyderabad 500 046 (India); Babu, P. D. [UGC-DAE Consortium for Scientific Research, R-5 Shed, B.A.R.C, Mumbai 400 085 (India)

2014-03-14T23:59:59.000Z

84

A revised structure and hydrogen bonding system in cellulose II from a neutron fiber diffraction analysis  

SciTech Connect

The crystal and molecular structure and hydrogen bonding system in cellulose II have been revised using new neutron diffraction data extending to 1.2 {angstrom} resolution collected from two highly crystalline fiber samples of mercerized flax. Mercerization was achieved in NaOH/H{sub 2}O for one sample and in NaOD/D{sub 2}O for the other, corresponding to the labile hydroxymethyl moieties being hydrogenated and deuterated, respectively. Fourier difference maps were calculated in which neutron difference amplitudes were combined with phases calculated from two revised X-ray models of cellulose II. The revised phasing models were determined by refinement against the X-ray data set of Kolpak and Blackwell, using the LALS methodology. Both models have two antiparallel chains organized in a P2{sub 1} space group and unit cell parameters: a = 8.01 {angstrom}, b = 9.04 {angstrom}, c = 10.36 {angstrom}, and {gamma} = 117.1{degree}. One has equivalent backbone conformations for both chains but different conformations for the hydroxymethyl moieties: gt for the origin chain and tg for the center chain. The second model based on the recent crystal structures of cellotetraose, has different conformations for the two chains but nearly equivalent conformations for the hydroxymethyl moieties. On the basis of the X-ray data alone, the models could not be differentiated. From the neutron Fourier difference maps, possible labile hydrogen atom positions were identified for each model and refined using LALS. The second model is significantly different from previous proposals based on the crystal structures of cellotetraose, MD simulations of cellulose II, and any potential hydrogen-bonding network in the structure of cellulose II determined in earlier X-ray fiber diffraction studies. The exact localization of the labile hydrogen atoms involved in this bonding, together with their donor and acceptor characteristics, is presented and discussed. This study provides, for the first time, the coordinates of all of the atoms in cellulose II.

Langan, P.; Nishiyama, Y.; Chanzy, H.

1999-11-03T23:59:59.000Z

85

Complex magnetic ordering in CeFe1.76 studied by neutron diffraction  

SciTech Connect

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 ?) with ??14 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 ?=14 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.

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

2014-10-01T23:59:59.000Z

86

Experimental determination of residual stress by neutron diffraction in a boiling water reactor core shroud  

SciTech Connect

Residual strains in a 51 mm (2-inch) thick 304L stainless steel plate have been measured by neutron diffraction and interpreted in terms of residual stress. The plate, measuring (300 mm) in area, was removed from a 6m (20-ft.) diameter unirradiated boiling water reactor core shroud, and included a multiple-pass horizontal weld which joined two of the cylindrical shells which comprise the core shroud. Residual stress mapping was undertaken in the heat affected zone, concentrating on the outside half of the plate thickness. Variations in residual stresses with location appeared consistent with trends expected from finite element calculations, considering that a large fraction of the residual hoop stress was released upon removal of the plate from the core shroud cylinder.

Payzant, A.; Spooner, S.; Zhu, Xiaojing; Hubbard, C.R. [and others

1996-06-01T23:59:59.000Z

87

Neutron Diffraction Study of the Magnetic Structure of Hematite to 41 kbar  

Science Journals Connector (OSTI)

Time-of-flight neutron diffraction has been used to study the pressure dependence of the magnetic moment direction in ?-Fe2O3 to 41 kbar. The pressure dependence of the magnetic moment direction at room temperature is found to be in agreement with the pressure dependence calculated from measurements of the quadrupole splitting at high pressure by Vaughan and Drickamer, using the Mssbauer effect. It is found that the spin direction varies slowly and continuously with pressure above 14 kbar, with no well-defined Morin transition occurring at room temperature. The large pressure dependence of the Morin transition at lower pressures is well accounted for by Searle's theory based on the magnetoelastic effect. The slow variation of the spin direction at higher pressures must be accounted for by higher-order contributions to the anisotropy energy.

T. G. Worlton and D. L. Decker

1968-07-10T23:59:59.000Z

88

Neutron diffraction determination of the residual stress redistribution in cracked autofrettaged tubing  

SciTech Connect

Neutron diffraction has been used to measure the residual stress distributions in uncracked and fatigue cracked rings taken from a high strength, low alloy steel autofrettage tube with a bore diameter of 60mm and a wall thickness of 32mm. Stresses were determined to a precision of {plus minus} 10MPa. Three crack sixes were examines. No appreciable stress redistribution was observed until the crack was grown into a region which originally contained tensile residual hoop stress. When this occurred an increase in residual hoop tension was observed ahead of the crick tip. Qualitative agreement was achieved between the measured hoop stress distribution and values predicted using a boundary element method. 9 refs., 12 figs.

Bourke, M.A. (Los Alamos National Lab., NM (USA)); McGillivray, H.J.; Webster, G.A. (Imperial Coll. of Science, Technology and Medicine, London (UK). Dept. of Mechanical Engineering); Webster, P.J. (Salford Univ. (UK). Dept. of Civil Engineering)

1991-01-01T23:59:59.000Z

89

Magnetic and crystal structures of Sr2IrO4: A neutron diffraction study  

Science Journals Connector (OSTI)

We report a single-crystal neutron diffraction study of the layered Sr2IrO4. This work unambiguously determines the magnetic structure of the system and reveals that the spin orientation rigidly tracks the staggered rotation of the IrO6 octahedra in Sr2IrO4. The long-range antiferromagnetic order has a canted spin configuration with an ordered moment of 0.208(3) ?B/Ir site within the basal plane; a detailed examination of the spin canting yields 0.202(3) and 0.049(2) ?B/site for the a axis and the b axis, respectively. It is intriguing that forbidden nuclear reflections of space group I41/acd are also observed in a wide temperature range from 4 K to 600 K, which suggests a reduced crystal structure symmetry. This neutron-scattering work provides a direct, well-refined experimental characterization of the magnetic and crystal structures that are crucial to the understanding of the unconventional magnetism exhibited in this unusual magnetic insulator.

Feng Ye, Songxue Chi, Bryan C. Chakoumakos, Jaime A. Fernandez-Baca, Tongfei Qi, and G. Cao

2013-04-22T23:59:59.000Z

90

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

SciTech Connect

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.

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

2014-01-01T23:59:59.000Z

91

First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments  

Science Journals Connector (OSTI)

A method to map spin-resolved electron distribution from combined polarized neutron and X-ray diffraction is described and applied for the first time to a molecular magnet and it is shown that spin up density is 5% more contracted than spin down density.

Deutsch, M.

2014-04-14T23:59:59.000Z

92

CO2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements  

Science Journals Connector (OSTI)

Neutron diffraction data and excess sorption isotherms were measured at 35 and 50 C and pressure ranges of 0200 bar, mimicking conditions of temperature and pressure in some of the currently active carbon storage sites (Kevin dome, Sleipner, Ketzin, Otway, Teapot dome). ...

Gernot Rother; Eugene S. Ilton; Dirk Wallacher; Thomas Hau?; Herbert T. Schaef; Odeta Qafoku; Kevin M. Rosso; Andrew R. Felmy; Elizabeth G. Krukowski; Andrew G. Stack; Nico Grimm; Robert J. Bodnar

2012-08-23T23:59:59.000Z

93

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

SciTech Connect

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.

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

2009-01-01T23:59:59.000Z

94

Refinement of the crystal structure of the high-temperature phase G0 in (NH4)2WO2F4 (powder, x-ray, and neutron scattering)  

SciTech Connect

The (NH4)2WO2F4 compound undergoes a series of phase transitions: G0 -> 201 K -> G1 -> 160 K -> G2, with a significant change in entropy ( S1 ~ Rln10 at the G0 -> G1 transition), which indicates significant orientational disordering in the G0 phase and the order disorder type of the phase transition. X-ray diffraction is used to identify the crystal structure of the G0 phase as rhombohedral (sp. gr. Cmcm, Z = 4), determine the lattice parameters and the positions of all atoms (except hydrogen), and show that [WO2F4]2 ions can form a superposition of dynamic and static orientational disorders in the anionic sublattice. A determination of the orientational position of [NH4]+ ions calls for the combined method of elastic and inelastic neutron scattering. Inelastic neutron scattering is used to determine the state of hindered rotation for ammonium ions in the G0 phase. Powder neutron diffraction shows that the orientational disorder of NH4 ions can adequately be described within the free rotation approximation.

Novak, D. M. [Joint Institute for Nuclear Research, Dubna, Russia; Smirnov, Lev S [Alikhanov Institute for Theoretical and Experimental Physics, Moscow, Russia; Kolesnikov, Alexander I [ORNL; Voronin, Vladimir [Institute of Metal Physics, Russia; Berger, I. F. [Institute of Metal Physics, Russia; Laptash, N. M. [Institute of Chemistry, Vladivostok, Russia; Vasil'ev, N. M. [Kirensky Institute of Physics, Krasnoyarsk, Russia; Flerov, I. N. [Kirensky Institute of Physics, Krasnoyarsk, Russia

2013-01-01T23:59:59.000Z

95

Refinement of the crystal structure of the high-temperature phase G{sub 0} in (NH{sub 4}){sub 2}WO{sub 2}F{sub 4} (powder, X-ray, and neutron scattering)  

SciTech Connect

The (NH{sub 4}){sub 2}WO{sub 2}F{sub 4} compound undergoes a series of phase transitions: G{sub 0} {yields} 201, K {yields} G{sub 1} {yields} 160, and K {yields} G{sub 2}, with a significant change in entropy ({Delta}S{sub 1} {approx} Rln10 at the G{sub 0} {yields} G{sub 1} transition), which indicates significant orientational disordering in the G{sub 0} phase and the order-disorder type of the phase transition. X-ray diffraction is used to identify the crystal structure of the G{sub 0} phase as rhombohedral (sp. gr. Cmcm, Z = 4), determine the lattice parameters and the positions of all atoms (except hydrogen), and show that [WO{sub 2}F{sub 4}]{sup 2-} ions can form a superposition of dynamic and static orientational disorders in the anionic sublattice. A determination of the orientational position of [NH{sub 4}]{sup +} ions calls for the combined method of elastic and inelastic neutron scattering. Inelastic neutron scattering is used to determine the state of hindered rotation for ammonium ions in the G{sub 0} phase. Powder neutron diffraction shows that the orientational disorder of NH{sub 4} ions can adequately be described within the free-rotation approximation.

Novak, D. M., E-mail: dmn@nf.jinr.ru; Smirnov, L. S. [Joint Institute for Nuclear Research, Frank Neutron Physics Laboratory (Russian Federation)] [Joint Institute for Nuclear Research, Frank Neutron Physics Laboratory (Russian Federation); Kolesnikov, A. I. [Oak Ridge National Laboratory, Neutron Scattering Sciences Division (United States)] [Oak Ridge National Laboratory, Neutron Scattering Sciences Division (United States); Voronin, V. I.; Berger, I. F. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation)] [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Laptash, N. M. [Russian Academy of Sciences, Institute of Chemistry, Far Eastern Branch (Russian Federation)] [Russian Academy of Sciences, Institute of Chemistry, Far Eastern Branch (Russian Federation); Vasil'ev, A. D.; Flerov, I. N. [Russian Academy of Sciences, Kirensky Institute of Physics, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Kirensky Institute of Physics, Siberian Branch (Russian Federation)

2013-01-15T23:59:59.000Z

96

Partial Spin Ordering and Complex Magnetic Structure in BaYFeO4: A Neutron Diffraction and High Temperature Susceptibility Study  

SciTech Connect

The novel iron-based compound, BaYFeO4, crystallizes in the Pnma space group with two distinct Fe3+ sites, that are alternately corner-shared [FeO5]7 square pyramids and [FeO6]9 octahedra, forming into [Fe4O18]24 rings, which propagate as columns along the b-axis. A recent report shows two discernible antiferromagnetic (AFM) transitions at 36 and 48 K in the susceptibility, yet heat capacity measurements reveal no magnetic phase transitions at these temperatures. An upturn in the magnetic susceptibility measurements up to 400 K suggests the presence of shortrange magnetic behavior at higher temperatures. In this Article, variable-temperature neutron powder diffraction and hightemperature magnetic susceptibility measurements were performed to clarify the magnetic behavior. Neutron powder diffraction confirmed that the two magnetic transitions observed at 36 and 48 K are due to long-range magnetic order. Below 48 K, the magnetic structure was determined as a spin-density wave (SDW) with a propagation vector, k = (0, 0, 1/3), and the moments along the b-axis, whereas the structure becomes an incommensurate cycloid [k = (0, 0, 0.35)] below 36 K with the moments within the bc-plane. However, for both cases the ordered moments on Fe3+ are only of the order 3.0 B, smaller than the expected values near 4.5 B, indicating that significant components of the Fe moments remain paramagnetic to the lowest temperature studied, 6 K. Moreover, new high-temperature magnetic susceptibility measurements revealed a peak maximum at 550 K indicative of short-range spin correlations. It is postulated that most of the magnetic entropy is thus removed at high temperatures which could explain the absence of heat capacity anomalies at the long-range ordering temperatures. Published spin dimer calculations, which appear to suggest a k = (0, 0, 0) magnetic structure, and allow for neither low dimensionality nor geometric frustration, are inadequate to explain the observed complex magnetic structure.

Thompson, Corey [Florida State University, Tallahassee] [Florida State University, Tallahassee; Greedan, John [McMaster University] [McMaster University; Garlea, Vasile O [ORNL] [ORNL; Flacau, Roxana [National Research Council of Canada] [National Research Council of Canada; Tan, Malinda [California State University, Long Beach (CSULB)] [California State University, Long Beach (CSULB); Derakhshan, Shahab [California State University, Long Beach (CSULB)] [California State University, Long Beach (CSULB)

2014-01-01T23:59:59.000Z

97

Neutron Diffraction Residual Strain Tensor Measurements Within The Phase IA Weld Mock-up Plate P-5  

SciTech Connect

Oak Ridge National Laboratory (ORNL) has worked with NRC and EPRI to apply neutron and X-ray diffraction methods to characterize the residual stresses in a number of dissimilar metal weld mockups and samples. The design of the Phase IA specimens aimed to enable stress measurements by several methods and computational modeling of the weld residual stresses. The partial groove in the 304L stainless steel plate was filled with weld beads of Alloy 82. A summary of the weld conditions for each plate is provided in Table 1. The plates were constrained along the long edges during and after welding by bolts with spring-loaded washers attached to the 1-inch thick Al backing plate. The purpose was to avoid stress relief due to bending of the welded stainless steel plate. The neutron diffraction method was one of the methods selected by EPRI for non-destructive through thickness strain and stress measurement. Four different plates (P-3 to P-6) were studied by neutron diffraction strain mapping, representing four different welding conditions. Through thickness neutron diffraction strain mappings at NRSF2 for the four plates and associated strain-free d-zero specimens involved measurement along seven lines across the weld and at six to seven depths. The mountings of each plate for neutron diffraction measurements were such that the diffraction vector was parallel to each of the three primary orthogonal directions of the plate: two in-plane directions, longitudinal and transverse, and the direction normal to the plate (shown in left figure within Table 1). From the three orthogonal strains for each location, the residual stresses along the three plate directions were calculated. The principal axes of the strain and stress tensors, however, need not necessarily align with the plate coordinate system. To explore this, plate P-5 was selected for examination of the possibility that the principal axes of strain are not along the sample coordinate system axes. If adequate data could be collected the goal would be to determine the strain tensor's orientation and magnitude of strain along each principle axis direction.

Hubbard, Camden R [ORNL

2011-09-01T23:59:59.000Z

98

Neutron reflectometry  

Science Journals Connector (OSTI)

Neutron reflectivity is a powerful tool for the ... chapter include: the theory of elastic specular neutron diffraction; polarized neutron reflectivity; surface roughness; experimental methodology; resolution in ...

G. S. Smith; C. F. Majkrzak

2004-01-01T23:59:59.000Z

99

Crystal Structures of the Trifluoromethyl Sulfonates M(SO3CF3)2 (M = Mg, Ca, Ba, Zn, Cu) from Synchrotron X-ray Powder Diffraction Data  

SciTech Connect

The crystal structures of divalent metal salts of trifluoromethyl sulfonic acid ('trifluoromethyl sulfonates') M(SO{sub 3}CF{sub 3}){sub 2} (M = Mg, Ca, Ba, Zn, Cu) were determined from high-resolution X-ray powder diffraction data. Magnesium, calcium and zinc trifluoromethyl sulfonate crystallize in the rhombohedral space group R{bar 3}. Barium trifluoromethyl sulfonate crystallizes in the monoclinic space group I2/a(C2/c) and copper trifluoromethyl sulfonate crystallizes in the triclinic group P{bar 1}. Within the crystal structures the trifluoromethyl sulfonate anions are arranged in double layers with the apolar CF{sub 3} groups pointing towards each other. The cations are located next to the SO{sub 3} groups. The symmetry relations between the different crystal structures have been analyzed.

Dinnebier,R.; Sofina, N.; Hildebrandt, L.; Jansen, M.

2006-01-01T23:59:59.000Z

100

Maximum Entropy Method and Charge Flipping, a Powerful Combination to Visualize the True Nature of Structural Disorder from in situ X-ray Powder Diffraction Data  

SciTech Connect

In a systematic approach, the ability of the Maximum Entropy Method (MEM) to reconstruct the most probable electron density of highly disordered crystal structures from X-ray powder diffraction data was evaluated. As a case study, the ambient temperature crystal structures of disordered {alpha}-Rb{sub 2}[C{sub 2}O{sub 4}] and {alpha}-Rb{sub 2}[CO{sub 3}] and ordered {delta}-K{sub 2}[C{sub 2}O{sub 4}] were investigated in detail with the aim of revealing the 'true' nature of the apparent disorder. Different combinations of F (based on phased structure factors) and G constraints (based on structure-factor amplitudes) from different sources were applied in MEM calculations. In particular, a new combination of the MEM with the recently developed charge-flipping algorithm with histogram matching for powder diffraction data (pCF) was successfully introduced to avoid the inevitable bias of the phases of the structure-factor amplitudes by the Rietveld model. Completely ab initio electron-density distributions have been obtained with the MEM applied to a combination of structure-factor amplitudes from Le Bail fits with phases derived from pCF. All features of the crystal structures, in particular the disorder of the oxalate and carbonate anions, and the displacements of the cations, are clearly obtained. This approach bears the potential of a fast method of electron-density determination, even for highly disordered materials. All the MEM maps obtained in this work were compared with the MEM map derived from the best Rietveld refined model. In general, the phased observed structure factors obtained from Rietveld refinement (applying F and G constraints) were found to give the closest description of the experimental data and thus lead to the most accurate image of the actual disorder.

Samy, A.; Dinnebier, R; van Smaalen, S; Jansen, M

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Ris-R-747(EN) Neutron and X-Ray Diffraction  

E-Print Network (OSTI)

describes X-ray and neutron scattering experiments per- formed on two examples of modulated structures is divided in three parts. A single crystal elastic neutron scattering experiment between 4.2 and 115 K has shift across the layers. A small-angle neutron scattering experiment has been performed on the mag

102

Neutron Experiment descriptions: N1: Triple-Axis Spectrometers, HFIR HB1A & HB3  

E-Print Network (OSTI)

Neutron Experiment descriptions: N1: Triple-Axis Spectrometers, HFIR HB1A & HB3 Spin wave2A Magnetic structure of NiO Neutron diffraction measurements will be performed to investigate 600K to 288K, using the Neutron Powder Diffractometer at the HFIR. Rietveld analysis of the crystal

Pennycook, Steve

103

JOURNAL DE PHYSIQUE Colloque C 1, supplment au n 2-3, Tome 32, Fvrier-Mars 1971, page C 1 -503 NEUTRON DIFFRACTION, MOSSBAUER  

E-Print Network (OSTI)

in neutron scattering amplitudes of Ti and V (b = - 0.38 and - 0.05 respectively) and Ta (b = 0.70 x 10- 1 2.17 (*) With temperature factor B = 0.4 A. The large contribution of oxygen to the neutron scattering permits us to refine NEUTRON DIFFRACTION, MOSSBAUER AND MAGNETIC INVESTIGATION OF RUTILE-TYPE TANTALATES MTa04 (M = Ti, V, Cr

Boyer, Edmond

104

Neutron Scattering and Diffraction Studies of Fluids and Fluid-Solid Interactions  

Science Journals Connector (OSTI)

...structure, such as porous glasses (e.g., Vycor), xerogels, aerogels, and rocks. At the other end, there are materials characterized...Frielinghaus H (2006) Adsorption of supercritical CO2 in aerogels as studied by small-angle neutron scattering and neutron...

David R. Cole; Kenneth W. Herwig; Eugene Mamontov; John Z. Larese

105

Visualizing the Structural Evolution of LSM/xYSZ Composite Cathodes for SOFC by in-situ Neutron Diffraction  

SciTech Connect

Composite cathodes for solid oxide fuel cells, the mixtures of (La0.8Sr0.2)0.95MnO3- (LSM) and (Y2O3)x(ZrO2)1-x (xYSZ, x = 3, 6, 8 and 10), have the thermal stability unraveled at elevated temperatures by using in-situ neutron diffraction. The Rietveld refinement analysis of neutron diffraction visualizes the phase evolutions and the ion activities in the material systems. The phase transition of tetragonal YSZ at T > 900 C leads to a heterogeneous redistribution of Mn ions. The reaction of LSM and YSZ occurring at T > 1100 C was revealed as a three-stage process, yielding La2Zr2O7, SrZrO3 and MnO. The activities of Y, Mn and La ions at elevated temperatures are derived by the structural analysis, and the three-stage reaction of YSZ and LSM was found strongly correlated to ions behaviors.

Chen, Yan [ORNL] [ORNL; Yang, Ling [ORNL] [ORNL; Ren, Fei [ORNL] [ORNL; An, Ke [ORNL] [ORNL

2014-01-01T23:59:59.000Z

106

Neutron diffraction studies of antiferromagnetism in manganous fluoride and some isomorphous compounds  

E-Print Network (OSTI)

. CALCULATED AND OBSERVED INTENSITIES MnF2..................53 VI. CALCULATED AND OBSERVED INTENSITIES FeF2..................57 VII. CALCULATED AND OBSERVED INTENSITIES CqF2..................62 VIII. CALCULATED AND OBSERVED INTENSITIES NiF2... 18. Diffraction Patterns from C0F2............................ 59 19. Saturation Curve of F2 in CoF0 and NiFo.................6l 100 2 2 20. NiF2 Diffraction Patterns................................0\\- 21. Saturation Curves for the Fluorides...

Erickson, Richard Ames

1952-01-01T23:59:59.000Z

107

WaterDNA interactions as studied by Xray and neutron fibre diffraction  

Science Journals Connector (OSTI)

...over the A form by the pres- ence of excess ions in the fibre. This effect is most...Langridge, R. 1965 Fourier synthesis of lithium DNA part III: Hoogsteen models. J...diffraction study of a crystalline form of the lithium salt. J. Mol. Biol. 2, 1937. Langridge...

2004-01-01T23:59:59.000Z

108

High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures  

SciTech Connect

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 BiNiO{sub 3} have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

Jacobsen, Matthew K.; Ridley, Christopher J.; Bocian, Artur; Kamenev, Konstantin V., E-mail: k.kamenev@ed.ac.uk [School of Engineering and CSEC, University of Edinburgh, Edinburgh (United Kingdom); Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry [ISIS, Rutherford Appleton Laboratory, Harwell Oxford (United Kingdom)] [ISIS, Rutherford Appleton Laboratory, Harwell Oxford (United Kingdom); Azuma, Masaki [Materials and Structures Laboratory, Tokyo Institute of Technology, Tokyo (Japan)] [Materials and Structures Laboratory, Tokyo Institute of Technology, Tokyo (Japan); Attfield, J. Paul [School of Chemistry and CSEC, University of Edinburgh, Edinburgh (United Kingdom)] [School of Chemistry and CSEC, University of Edinburgh, Edinburgh (United Kingdom)

2014-04-15T23:59:59.000Z

109

Nanosecond molecular relaxations in lipid bilayers studied by high energy resolution neutron scattering and in-situ diffraction  

E-Print Network (OSTI)

We report a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid supported phospholipid bilayers of the model system DMPC -d54 (deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water. Wave vector resolved quasi-elastic neutron scattering (QENS) is used to determine relaxation times $\\tau$, which can be associated with different molecular components, i.e., the lipid acyl chains and the interstitial water molecules in the different phases of the model membrane system. The inelastic data are complemented both by energy resolved and energy integrated in-situ diffraction. From a combined analysis of the inelastic data in the energy and time domain, the respective character of the relaxation, i.e., the exponent of the exponential decay is also determined. From this analysis we quantify two relaxation processes. We associate the fast relaxation with translational diffusion of lipid and water molecules while the slow process likely stems from collective dynamics.

Maikel C. Rheinstdter; Tilo Seydel; Tim Salditt

2006-07-20T23:59:59.000Z

110

Combined Neutron and Synchrotron X-ray Diffraction Investigation of the BaCe0.85-xZrxY0.15O3-? (0.1 ? x ? 0.4) Proton Conductors  

Science Journals Connector (OSTI)

Combined Neutron and Synchrotron X-ray Diffraction Investigation of the BaCe0.85-xZrxY0.15O3-? (0.1 ? x ? 0.4) Proton Conductors ... Laboratory for Neutron Scattering, ETHZ and PSI, CH-5232, Villigen PSI, Switzerland ... Combined neutron and X-ray synchrotron diffraction have been used to unveil the structural properties for the BaCe0.85-xZrxY0.15O3-? ...

Lorenzo Malavasi; Cristina Tealdi; Clemens Ritter; Vladimir Pomjakushin; Fabia Gozzo; Yuri Diaz-Fernandez

2011-02-03T23:59:59.000Z

111

JOURNAL DE PHYSIQUE Colloque C I, supplPment au no 2-3, Tome 32, FPvrier-Mars 1971,page C 1 -70 NEUTRON DIFFRACTION STUDY OF SHORT RANGE ORDER  

E-Print Network (OSTI)

cross-section for neutron scattering is do -dQ = m~ m~(b, - bd2 i=o ai exp i(K.Ri) (I) where ai = 1 - Pi NEUTRON DIFFRACTION STUDY OF SHORT RANGE ORDER IN r-iMnNi P. WELLS and J. H. SMITH Physics Department un moment magnetique par atome de manganese de 1,5 +. 0,l WB. Une etude par diffraction de neutrons r

Boyer, Edmond

112

Contacts | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Science Points of Contact Science Points of Contact Name Research Area Doug Abernathy Wide Angular-Range Chopper Spectrometer (ARCS). Atomic-scale dynamics at thermal and epithermal energies Ke An Engineering Materials Diffractometer (VULCAN). Residual stress, deformation mechanism of materials, phase transitions/transformation, and in situ/operando neutron diffraction in material systems (e.g., working batteries). John Ankner Liquids Reflectometer (LR). Density profiles normal to the surface at liquid surfaces and liquid interfaces Bryan Chakoumakos Nuclear and magnetic crystal structure systematics and structure-property relationships among inorganic materials, powder and single-crystal neutron and x-ray diffraction methods Leighton Coates Macromolecular Neutron Diffractometer (MaNDi). Protein crystallography, biological structure and function

113

JOURNAL DE PHYSIQUE CoZZoque C8, suppZ6ment au n08, Tome 41, aoGt 1980, page C8-163 STUDY OF LIQUID NICKEL-VANADIUM ALLOYS BY NEUTRON DIFFRACTION AND MODEL SIMULATION  

E-Print Network (OSTI)

, 28 i s the scattering angle, X the neutron wave- length, Q = 4n the modulus of the scattering vector NICKEL-VANADIUM ALLOYS BY NEUTRON DIFFRACTION AND MODEL SIMULATION J.L. Lemarchand, J. Bletry and P with model c a l c u l a t i o ~can lead to a quantitative interpreta- tion. In this paper, neutron

Boyer, Edmond

114

A Novel In-situ Electrochemical Cell for Neutron Diffraction Studies of Phase Transitions in Small Volume Electrodes of Li-ion Batteries  

SciTech Connect

The design and performance of a novel in-situ electrochemical cell that greatly facilitates the neutron diffraction study of complex phase transitions in small volume electrodes of Li-ion cells, is presented in this work. Diffraction patterns that are Rietveld-refinable could be obtained simultaneously for all the electrodes, which demonstrates that the cell is best suited to explore electrode phase transitions driven by the lithiation and delithiation processes. This has been facilitated by the use of single crystal (100) Si sheets as casing material and the planar cell configuration, giving improved signal-to-noise ratio relative to other casing materials. The in-situ cell has also been designed for easy assembly and to facilitate rapid experiments. The effectiveness of cell is demonstrated by tracking the neutron diffraction patterns during the charging of graphite/LiCoO2 and graphite/LiMn2O4 cells. It is shown that good quality neutron diffraction data can be obtained and that most of the finer details of the phase transitions, and the associated changes in crystallographic parameters in these electrodes, can be captured.

Vadlamani, Bhaskar S [ORNL; An, Ke [ORNL; Jagannathan, M. [University of Utah; Ravi Chandran, K. [University of Utah

2014-01-01T23:59:59.000Z

115

Development of a Neutron Diffraction Based Experiemental Capability for Investigating Hydraulic Fracturing for EGS-like Conditions  

SciTech Connect

Hydraulic fracturing to enhance formation permeability is an established practice in the Oil & Gas (O&G) industry and is expected to be an enabler for EGS. However, it is rarely employed in conventional geothermal systems and there are significant questions regarding the translation of practice from O&G to both conventional geothermal and EGS applications. Lithological differences(sedimentary versus crystalline rocks, significantly greater formation temperatures and different desired fracture characteristics are among a number of factors that are likely to result in a gap of understanding of how to manage hydraulic fracturing practice for geothermal. Whereas the O&G community has had both the capital and the opportunity to develop its understanding of hydraulic fracturing operations empirically in the field as well through extensive R&D efforts, field testing opportunities for EGS are likely to be minimal due to the high expense of hydraulic fracturing field trials. A significant portion of the knowledge needed to guide the management of geothermal/EGS hydraulic fracturing operations will therefore likely have to come from experimental efforts and simulation. This paper describes ongoing efforts at Oak Ridge National Laboratory (ORNL) to develop an experimental capability to map the internal stresses/strains in core samples subjected to triaxial stress states and temperatures representative of EGS-like conditions using neutron diffraction based strain mapping techniques. This capability is being developed at ORNL\\'s Spallation Neutron Source, the world\\'s most powerful pulsed neutron source and is still in a proof of concept phase. A specialized pressure cell has been developed that permits independent radial and axial fluid pressurization of core samples, with axial flow through capability and a temperature rating up to 300 degrees C. This cell will ultimately be used to hydraulically pressurize EGS-representative core samples to conditions of imminent fracture and map the associated internal strain states of the sample. This will hopefully enable a more precise mapping of the rock material failure envelope, facilitate a more refined understanding of the mechanism of hydraulically induced rock fracture, particularly in crystalline rocks, and serve as a platform for validating and improving fracture simulation codes. The elements of the research program and preliminary strain mapping results of a Sierra White granite sample subjected only to compressive loading will be discussed in this paper.

Polsky, Yarom [ORNL] [ORNL; Anovitz, Lawrence {Larry} M [ORNL; An, Ke [ORNL] [ORNL; Carmichael, Justin R [ORNL] [ORNL; Bingham, Philip R [ORNL] [ORNL; Dessieux Jr, Luc Lucius [ORNL] [ORNL

2013-01-01T23:59:59.000Z

116

X-Ray Diffraction The X-Ray Diffraction facility is equipped with state-of-the-art  

E-Print Network (OSTI)

X-Ray Diffraction The X-Ray Diffraction facility is equipped with state-of-the-art diffractometers offering both single crystal and powder X-Ray diffraction. Powder X-Ray Diffraction High resolution data For more details on powder X-Ray analysis contact Dr J Hriljac on 0121 414 4458 or email: j

Birmingham, University of

117

Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction  

Science Journals Connector (OSTI)

Two-dimensional position-sensitive gaseous detectors have been developed at the Geesthacht Neutron Facility (GeNF) for high-resolution...2, 3He/CF4 and Xe/CO2, respectively. One neutron detector is used at the AR...

M. Marmotti; M. Haese-Seiller; R. Kampmann

2002-12-01T23:59:59.000Z

118

Neutron Scattering  

Science Journals Connector (OSTI)

... Magnetic Neutron Diffraction By Yurii A. Izyumov and Ruslan P. Ozerov. Translated from the Russian. ... York; Heydon: London, June 1970.) 350s; $37.50; 150 DM.

G. L. SQUIRES

1970-12-05T23:59:59.000Z

119

A high temperature neutron diffraction study of the double perovskite Ba{sub 2}{sup 154}SmMoO{sub 6}  

SciTech Connect

Ba{sub 2}LnMoO{sub 6} double perovskites have been recently shown to display a wide range of interesting magnetic and structural properties; Ba{sub 2}{sup 154}SmMoO{sub 6} exhibits simultaneous antiferromagnetic order and a Jahn-Teller distortion. Here we report a high temperature neutron diffraction study of Ba{sub 2}{sup 154}SmMoO{sub 6} from 353 to 877 K. The results evidence a tetragonal to cubic phase transition at 423 K. Above this temperature the thermal displacement parameters of the oxygen atoms are modelled anisotropically as a result of a transverse vibration of the bridging oxygen. A smooth increase in the cell parameter a is observed with temperature for Ba{sub 2}{sup 154}SmMoO{sub 6}. - Graphical abstract: The high temperature crystal structure of Ba{sub 2}{sup 154}SmMoO{sub 6} evidencing a transverse oxygen vibration. Highlights: Black-Right-Pointing-Pointer A high temperature neutron diffraction study has been performed on an isotopically enriched sample of Ba{sub 2}{sup 154}SmMoO{sub 6}. Black-Right-Pointing-Pointer A cubic-tetragonal phase transition occurs below 423 K. Black-Right-Pointing-Pointer The thermal displacement parameters of the bridging oxygens are modelled anisotropically. Black-Right-Pointing-Pointer There is a transverse vibration of the bridging oxygen.

Wallace, Thomas K. [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom)] [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom); Ritter, Clemens [Institut Laue Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble Cedex 9 (France)] [Institut Laue Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble Cedex 9 (France); Mclaughlin, Abbie C., E-mail: a.c.mclaughlin@abdn.ac.uk [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom)

2012-12-15T23:59:59.000Z

120

Agglomeration and sintering in annealed FePt nanoparticle assemblies studied by small angle neutron scattering and x-ray diffraction  

Science Journals Connector (OSTI)

In this work we give a detailed account of complementary small angle neutron scattering and x-ray diffraction studies of polymer mediated, self-assembled FePt nanoparticle arrays as a function of annealing temperature. The combination of these two techniques provides significantly greater physical insight than is available using either individually. Since both methods integrate over a large number of particles statistically meaningful data can be obtained in contrast to imaging techniques where typically only small areas are analyzed. The data show that the median particle size increases with annealing at temperatures of 580C and above. The data also demonstrate that the distribution of particle diameters is significant and increases with annealing temperature. These results allow a comprehensive structural model of the annealed assemblies to be developed in terms of particle sintering and agglomeration. This enhanced understanding will allow new strategies to be pursued in realizing the potential of nanoparticle assemblies as a monodispersed data storage medium.

T. Thomson; S. L. Lee; M. F. Toney; C. D. Dewhurst; F. Y. Ogrin; C. J. Oates; S. Sun

2005-08-19T23:59:59.000Z

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121

Principal interactions in the magnetic system Fe{sub 1-x}Co{sub x}Si: Magnetic structure and critical temperature by neutron diffraction and SQUID measurements  

SciTech Connect

The compound Fe{sub 1-x}Co{sub x}Si is a good representative for a cubic magnet with Dzyaloshinskii-Moriya interaction. On the basis of the neutron diffraction and superconducting quantum interference device measurements, we built the H-T phase diagram for the compound with different x from 0.1 to 0.7. The same set of parameters governs the magnetic system for different x. These parameters are well interpreted in the framework of the recently developed theory [S. V. Maleyev, Phys. Rev. B 73, 174402 (2006)]. As a result, the spin-wave stiffness, the Dzyaloshinskii constant, the anisotropic exchange constant, and the spin-wave gap caused by the Dzyaloshinskii interaction have been obtained and plotted as a function of x. The changes of the magnetic structure with x can be well interpreted on the basis of our findings.

Grigoriev, S. V.; Maleyev, S. V.; Dyadkin, V. A. [Petersburg Nuclear Physics Institute, Gatchina, 188300 St. Petersburg (Russian Federation); Menzel, D.; Schoenes, J. [Institut fuer Physik der Kondensierten Materie, TU Braunschweig, 38106 Braunschweig (Germany); Eckerlebe, H. [GKSS Forschungszentrum, 21502 Geesthacht (Germany)

2007-09-01T23:59:59.000Z

122

Features of Diffraction Dissociation of Neutrons in np Collisions at 50-300 GeV/c  

Science Journals Connector (OSTI)

We present preliminary results from an investigation of the reaction n+p?(p?-)+p for neutron momenta in the range of 50 to 300 GeV/c. The data display a strong correlation between the mass of the p?- system and the four-momentum transferred in the production. Cross sections for producing low-mass (p?-) systems are independent of energy to within 10% accuracy.

J. Biel; E. Bleser; T. Ferbel; D. Freytag; B. Gobbi; L. Kenah; J. Rosen; R. Ruchti; P. Slattery; D. Underwood

1976-03-08T23:59:59.000Z

123

Closed three-center carbon-hydrogen-metal interaction. A neutron diffraction study of HFe/sub 4/(eta/sup 2/-CH)(CO)/sub 12/  

SciTech Connect

The crystal and molecular structure of HFe/sub 4/(eta/sup 2/-CH)(CO)/sub 12/ has been determined at 173 K by x-ray diffraction and at 26 K by neutron diffraction techniques. The complex crystallized in the monoclinic space group with unit-cell dimensions of a = 8.694 (1) A, b = 32.920 (6) A, c = 13.757 (3) A, ..beta.. = 112.95 (1)/sup 0/, and V = 3625.7 A/sup 3/ at 26 K with Z = 8. Full-matrix least-squares refinement of the neutron data gave R(F/sub 0/) = 0.060 and R/sub w/(F/sub 0//sup 2/) = 0.079 for all 5663 data. The goodness-of-fit, with a data to parameter ratio of 10.1:1, was 1.876. The only significant structural differences in the two unique molecules of the asymmetric unit were the intermolecular contacts. The iron atoms were arranged in a butterfly conformation with a C-H group nestled between the wings. The most significant structural finding was a true C-H-Fe three-center interaction, containing both a very short Fe-H distance of 1.753 (4) A (1.747 (4) A, second molecule) and the longest reported C-H bond distance, 1.191 (4) A (1.176 (4) A). The results have been discussed in relation to the origin and nature of this C-H-Fe three-center interaction, the activation of C-H bonds in catalysis, and possible eta/sup 2/ bonding of a C-H fragment at a metal surface.

Beno, M.A. (Argonne National Lab., IL); Williams, J.M.; Tachikawa, M.; Muetterties, E.L.

1981-03-25T23:59:59.000Z

124

Assessment of the optimum degree of Sr{sub 3}Fe{sub 2}MoO{sub 9} electron-doping through oxygen removal: An X-ray powder diffraction and {sup 57}Fe Moessbauer spectroscopy study  

SciTech Connect

We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Moessbauer spectroscopy of three electron-doped perovskites Sr{sub 3}Fe{sub 2}MoO{sub 9-{delta}} with Fe/Mo = 2 obtained from Sr{sub 3}Fe{sub 2}MoO{sub 9}. The compounds were synthesized by topotactic reduction with H{sub 2}/N{sub 2} (5/95) at 600, 700 and 800 {sup o}C. Above 800 {sup o}C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group Fm3-bar m, with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Moessbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 {sup o}C are only in the high-spin Fe{sup 3+} electronic state.

Lopez, Carlos A.; Viola, Maria del C. [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina)] [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Pedregosa, Jose C., E-mail: jpedreg@unsl.edu.ar [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Mercader, Roberto C., E-mail: mercader@fisica.unlp.edu.ar [Departamento de Fisica, IFLP-CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina)

2010-10-15T23:59:59.000Z

125

Bulk microstructure in a strained cohesive powder R. Andersson,1,  

E-Print Network (OSTI)

Neutron Scattering is able to characterise powders in terms of their density- density correlation function, 61.12.Ex, 81.05.Rm Keywords: Powder, Cohesion, Microstructure, Small-Angle Neutron Scattering, SESANS Resonance Imaging [5, 6]. Spin Echo Small Angle Neutron Scattering (SESANS) is using the penetrating ability

Luding, Stefan

126

WAND: Wide-Angle Neutron Diffractometer at HFIR | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

US/Japan Wide-Angle Neutron Diffractometer US/Japan Wide-Angle Neutron Diffractometer WAND Instrument scientist Jaime Fernandez-Baca (left) with a visiting researcher at WAND. The Wide-Angle Neutron Diffractometer (WAND) at the HFIR HB-2C beam tube was designed to provide two specialized data-collection capabilities: (1) fast measurements of medium-resolution powder-diffraction patterns and (2) measurements of diffuse scattering in single crystals using flat-cone geometry. For these purposes, this instrument is equipped with a curved, one-dimensional 3He position-sensitive detector covering 125º of the scattering angle with the focal distance of 71 cm. The sample and detector can be tilted in the flat-cone geometry mode. These features enable measurement of single-crystal diffraction patterns in a short time over a

127

Neutron and X-ray diffraction studies on the high temperature phase of Mn{sub 3}(VO{sub 4}){sub 2}, the new isostructural compound NaMn{sub 4}(VO{sub 4}){sub 3} and their mixed crystals Na{sub x}Mn{sub 4.5-x/2}(VO{sub 4}){sub 3} (0{<=}x{<=}1)  

SciTech Connect

This paper presents a detailed structure analysis (combined Rietveld analysis of X-ray and neutron powder diffraction data as well as quantum mechanical calculations) of the high temperature phase of Mn{sub 3}(VO{sub 4}){sub 2} (space group I4 Macron 2d). Special attention is directed to the analysis of the local coordination around Mn{sup 2+} ions or vacancies within a stella quadrangula configuration of anions. Furthermore, the new compound NaMn{sub 4}(VO{sub 4}){sub 3} is described as well as a range of mixed crystals between NaMn{sub 4}(VO{sub 4}){sub 3} and Mn{sub 3}(VO{sub 4}){sub 2} (described by the formula Na{sub x}Mn{sub 4.5-x/2}(VO{sub 4}){sub 3}, 0{<=}x{<=}1) which were synthesized by a solid state route. All compounds were shown to be isostructural to the high temperature phase Mn{sub 3}(VO{sub 4}){sub 2}. - Graphical abstract: The crystal structure of the new compound NaMn{sub 4}(VO{sub 4}){sub 3}. Highlights: Black-Right-Pointing-Pointer We present neutron and X-ray diffraction studies on high temperature-Mn{sub 3}(VO{sub 4}){sub 2}. Black-Right-Pointing-Pointer Structural details of partly filled stellae quadrangulae positions are discussed. Black-Right-Pointing-Pointer Refined structural parameters and theoretical calculations are compared. Black-Right-Pointing-Pointer We investigate the mixed crystal system Mn{sub 3}(VO{sub 4}){sub 2}-NaMn{sub 4}(VO{sub 4}){sub 3}.

Clemens, Oliver [Universitaet des Saarlandes, Institut fuer Anorganische und Analytische Chemie und Radiochemie, Am Markt, Zeile 5, 66125 Saarbruecken (Germany)] [Universitaet des Saarlandes, Institut fuer Anorganische und Analytische Chemie und Radiochemie, Am Markt, Zeile 5, 66125 Saarbruecken (Germany); Haberkorn, Robert [Universitaet des Saarlandes, Anorganische Festkoerperchemie, Am Markt, Zeile 3, 66125 Saarbruecken (Germany)] [Universitaet des Saarlandes, Anorganische Festkoerperchemie, Am Markt, Zeile 3, 66125 Saarbruecken (Germany); Springborg, Michael [Universitaet des Saarlandes, Physikalische und Theoretische Chemie, Campus B2 2, 66123 Saarbruecken (Germany)] [Universitaet des Saarlandes, Physikalische und Theoretische Chemie, Campus B2 2, 66123 Saarbruecken (Germany); Beck, Horst Philipp, E-mail: hp.beck@mx.uni-saarland.de [Universitaet des Saarlandes, Institut fuer Anorganische und Analytische Chemie und Radiochemie, Am Markt, Zeile 5, 66125 Saarbruecken (Germany)

2012-10-15T23:59:59.000Z

128

Magnetic measurements and neutron diffraction study of the layered hybrid compounds Mn(C{sub 8}H{sub 4}O{sub 4})(H{sub 2}O){sub 2} and Mn{sub 2}(OH){sub 2}(C{sub 8}H{sub 4}O{sub 4})  

SciTech Connect

Mn(C{sub 8}H{sub 4}O{sub 4})(H{sub 2}O){sub 2} and Mn{sub 2}(OH){sub 2}(C{sub 8}H{sub 4}O{sub 4}) layered organic-inorganic compounds based on manganese(II) and terephthalate molecules (C{sub 8}H{sub 4}O{sub 4}{sup 2-}) have been studied by DC and AC magnetic measurements and powder neutron diffraction. The dihydrated compound behaves as a 3D antiferromagnet below 6.5 K. The temperature dependence of its {chi}T product is typical of a 2D Heisenberg system and allows determining the in-plane exchange constant J Almost-Equal-To -7.4 K through the carboxylate bridges. The magnetic structure confirms the in-plane nearest neighbor antiferromagnetic interactions and the 3D ordering. The hydroxide based compound also orders as a 3D antiferromagnet with a higher Neel temperature (38.5 K). Its magnetic structure is described from two antiferromagnetically coupled ferromagnetic sublattices, in relation with the two independent metallic sites. The isothermal magnetization data at 2 K are consistent with the antiferromagnetic ground-state of these compounds. However, in both cases, a slope change points to field-induced modification of the magnetic structure. - Graphical abstract: The macroscopic magnetic properties and magnetic structures of two metal-organic frameworks based on manganese (II) and terephthalate molecules are presented. Highlights: Black-Right-Pointing-Pointer Magnetic study of Mn(C{sub 8}H{sub 4}O{sub 4})(H{sub 2}O){sub 2} and Mn{sub 2}(OH){sub 2}(C{sub 8}H{sub 4}O{sub 4}). Black-Right-Pointing-Pointer Two compounds with common features (interlayer linker/distance, S=5/2 spin). Black-Right-Pointing-Pointer Magnetic measurements quantitatively analyzed to deduce exchange constants. Black-Right-Pointing-Pointer Magnetic structures determined from neutron powder diffraction experiments.

Sibille, Romain, E-mail: romain.sibille@ijl.nancy-universite.fr [Institut Jean Lamour, UMR 7198-Nancy Universite, BP 70239, 54506 Vandoeuvre-les-Nancy Cedex (France); Mesbah, Adel; Mazet, Thomas; Malaman, Bernard [Institut Jean Lamour, UMR 7198-Nancy Universite, BP 70239, 54506 Vandoeuvre-les-Nancy Cedex (France); Capelli, Silvia [Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Francois, Michel [Institut Jean Lamour, UMR 7198-Nancy Universite, BP 70239, 54506 Vandoeuvre-les-Nancy Cedex (France)

2012-02-15T23:59:59.000Z

129

Heterolytic Cleavage of Hydrogen by an Iron Hydrogenase Model: An Fe-H - - - H-N Dihydorgen Bond Characterized by Neutron Diffraction  

SciTech Connect

Use of hydrogen as a fuel by [FeFe]-hydrogenase enzymes in nature requires heterolytic cleavage of the H-H bond into a proton (H+) and hydride (H-), a reaction that is also a critical step in homogeneous catalysts for hydrogenation of C=O and C=N bonds. An understanding of the catalytic oxidation of H2 by hydrogenases provides insights into the design of synthetic catalysts that are sought as cost-effective alternatives to the use of the precious metal platinum in fuel cells. Crystallographic studies on the [FeFe]-hydrogenase enzyme were critical to understanding of its reactivity, but the key H-H cleavage step is not readily observed experimentally in natural hydrogenases. Synthetic biomimics have provided evidence for H2 cleavage leading to hydride transfer to the metal and proton transfer to an amine. Limitations on the precise location of hydrogen atoms by x-ray diffraction can be overcome by use of neutron diffraction, though its use is severely limited by the difficulty of obtaining suitable crystals and by the scarcity of neutron sources. Here we show that an iron complex with a pendant amine in the diphosphine ligand cleaves hydrogen heterolytically under mild conditions, leading to [CpC5F4NFeH(PtBu2NtBu2H)]+BArF4-, [PtBu2NtBu2 = 1,5-di(tert-butyl)-3,7-di(tert-butyl)-1,5-diaza-3,7-diphosphacyclooctane; ArF = 3,5-bis(trifluoromethyl)phenyl]. The Fe-H- - - H-N moiety has a strong dihydrogen bond, with a remarkably short H H distance of 1.489(10) between the protic N-H?+ and hydridic Fe-H?-. The structural data for [CpC5F4NFeH(PtBu2NtBu2H)]+ provide a glimpse of how the H-H bond is oxidized or generated in hydrogenase enzymes, with the pendant amine playing a key role as a proton relay. The iron complex [CpC5F4NFeH(PtBu2NtBu2H)]+BArF4- is an electrocatalyst for oxidation of H2 (1 atm) at 22 C, so the structural data are obtained on a complex that is a functional model for catalysis by [FeFe]-hydrogenase enzymes. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

Liu, Tianbiao L.; Wang, Xiaoping; Hoffmann, Christina; DuBois, Daniel L.; Bullock, R. Morris

2014-05-19T23:59:59.000Z

130

Magnetic structure of Fe{sub 1-x}Co{sub x}Si in a magnetic field studied via small-angle polarized neutron diffraction  

SciTech Connect

The magnetic structure of Fe{sub 1-x}Co{sub x}Si single crystals with x=0.10,0.15,0.20,0.50 has been studied by small angle polarized neutron diffraction and superconducting quantum interference device measurements. Experiments have shown that in zero field the compounds with x=0.1,0.15 have a well-defined tendency to order in the one-handed spiral along <100> axes due to the anisotropic exchange, that, however, decreases with increasing Co concentration x. The magnetic structure of Fe{sub 1-x}Co{sub x}Si with x=0.2,0.5 consists of spiral domains with randomly oriented spiral wave vector k. The applied magnetic field produces a single domain helix oriented along the field. The process of the reorientation starts at the field H{sub C1}. Further increase of the field leads to a magnetic phase transition from a conical to a ferromagnetic state near H{sub C2}. In the critical range near T{sub C} the integral intensity of the Bragg reflection shows a well-pronounced minimum at H{sub fl} attributed to a k flop of the helix wave vector. On the basis of our experiments we built the H-T phase diagram for each compound. It is shown that the same set of the parameters governs the magnetic properties of these compounds k, H{sub C1}, H{sub fl}, and H{sub C2}. Our experimental findings are well interpreted in the framework of a recently developed theory [Phys. Rev. B 73, 174402 (2006)] for cubic magnets with Dzyaloshinskii-Moriya (DM) interaction. In particular, the theory suggests an additional quantum term in the magnetic susceptibility caused by the DM interaction which is in good agreement with the experiment.

Grigoriev, S. V.; Dyadkin, V. A.; Chetverikov, Yu. O.; Okorokov, A. I.; Maleyev, S. V. [Petersburg Nuclear Physics Institute, Gatchina, 188300 St-Petersburg (Russian Federation); Menzel, D.; Schoenes, J. [Institut fuer Physik der Kondensierten Materie, Technische Universitaet Braunschweig, D-38106 Braunschweig (Germany); Eckerlebe, H. [GKSS Forschungszentrum, 21502 Geesthacht (Germany)

2007-12-01T23:59:59.000Z

131

Neutron diffraction structural study of pyroelectric Li/sub 2/SO/sub 4/xH/sub 2/O at 293, 80, and 20 K  

SciTech Connect

Lithium sulfate monohydrate has been studied at 293, 80, and 20 K by neutron diffraction using the same ground spherical crystal. Li/sub 2/SO/sub 4/xH/sub 2/O is monoclinic, space group P2/sub 1/, with lattice dimensions at 293 K of a = 5.450(3), b = 4.872(3), c = 8.164(4) A, ..beta.. = 107.31(3)/sup 0/; at 80 K: a = 5.449(2), b = 4.832(2), c = 8.141(2) A, ..beta.. = 107.21(1)/sup 0/; and at 20 K: a = 5.449(2), b = 4.832(2), c = 8.137(2) A, ..beta.. = 107.19(1)/sup 0/. There are two formula units in the unit cell. Least-squares refinement based on 1749 (293 K), 1712 (80 K), and 880 (20 K) reflections gave final R(F) values of 0.022, 0.016, and 0.014, respectively. All structure factors were corrected for thermal diffuse scattering. A Gram--Charlier expansion of the probability density function was used to describe the thermal vibrations of the water molecule which at 293 K are consistent with a previously postulated flipping motion. The O(W)xxxO(W) hydrogen bond distance is 0.091(3) A shorter and the O(W)xxxO(W)xxxO(W) angle is 3.9(1)/sup 0/ larger at 20 K than at 293 K: the O(W)xxxO(1) distance to a sulfate oxygen is 0.041(3) A shorter. Both kinds of hydrogen bonds are weak and bent.

Lundgren, J.; Kvick; Karppinen, M.; Liminga, R.; Abrahams, S.C.

1984-01-01T23:59:59.000Z

132

Elimination of ghosting artifacts from wavelength-shifting fiber neutron detectors  

SciTech Connect

Misassignment of neutron position (ghosting) produces artifacts which have been observed in wavelength-shifting (WLS) fiber detectors developed for time-of-flight (TOF) neutron powder diffraction. In position-sensitive detectors (PSDs) with WLS fiber encoding, thermal and cold neutrons interact with a monolithic {sup 6}LiF/ZnS:Ag scintillator screen, and scintillation photons are generated and transported through the crossed fibers to photomultipliers (PMTs). The neutron position is determined by photon counts in the PMTs within a preset time window. Ghosting occurs when neutrons hit the group boundaries of two neighboring PMTs for x-position multiplexing, which is modeled as resulting from a long travel length (about 3-5 mm) of a small number of scintillation photons. This model is supported by the change observed in aperture images when the threshold number for photon-pulses was adjusted for neutron event determination. When the threshold number of photon-pulses was set above 10 for each PMT, the ghost peaks in the aperture images and TOF spectra of powder diffraction were strongly suppressed or completely eliminated, and the intrinsic background levels of the WLS detectors were significantly reduced. Our result indicates that WLS fiber detector is a promising alternative for {sup 3}He PSDs for neutron scattering.

Wang, C. L.; Diawara, Y.; Hannan, B. W.; Hodges, J. P. [Instrument and Source Design Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Clonts, L. G. [Research Accelerator Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2013-01-15T23:59:59.000Z

133

Cryogenic neutron protein crystallography: routine methods and potential benefits  

Science Journals Connector (OSTI)

This article highlights routine methods and the benefits of collecting cryogenic macromolecular neutron diffraction data.

Coates, L.

2014-06-14T23:59:59.000Z

134

Neutron diffraction and specific heat studies on the magnetic ordering in the [Fe{sup II}({delta})Fe{sup II}({lambda})(ox){sub 2}(Phen){sub 2}]{sub n} molecular magnet  

SciTech Connect

The magnetic characteristics of the molecular magnet [Fe{sup II}({delta})Fe{sup II}({lambda})(ox){sub 2}(Phen){sub 2}]{sub n}, having chemical formula C{sub 28}H{sub 16}Fe{sub 2}N{sub 4}O{sub 8} for unity, has been studied by magnetization, neutron diffraction, and field-dependent specific heat-measurements. In the high-temperature regime (T>T{sub m}), the one-dimensional Ising chain model with alternate Lande factors is applied to describe its quasiferrimagnetic behavior as temperature approaches T{sub m}. In the low-temperature region (Tneutron diffraction study. The field-dependent {lambda}-type anomaly of specific heat indicates that applying a magnetic field raises magnetic ordering temperature. An additional small anomaly in specific heat is also seen below T{sub m}, which could be due to the zero-field splitting caused by the internal crystal field.

Ho, C. J.; Her, J. L.; Sun, C. P.; Huang, C. L.; Chou, C. C.; Yang, H. D. [Department of Physics, Center of Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Yang, C. C.; Li, W. H. [Department of Physics and Center for Neutron Beam Applications, National Central University, Chung-Li 32054, Taiwan (China); Li Lulin; Lin, K. J. [Department of Chemistry, Center of Nanoscience and Nanotechnology, National Chung-Hsing University, Taichung 402, Taiwan (China); Lynn, J. W. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2007-12-01T23:59:59.000Z

135

Small-angle neutron scattering and neutron reflectometry  

Science Journals Connector (OSTI)

Diffraction methods, interpreted loosely, could be applied to the techniques of wide-angle X-ray scattering, small-angle X-ray scattering, electron diffraction, small-angle neutron scattering, small-angle light s...

R. W. Richards

1993-01-01T23:59:59.000Z

136

Science | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Science Neutron Science Neutron Scattering Science Neutrons are one of the fundamental particles that make up matter and have properties that make them ideal for certain types of research. In the universe, neutrons are abundant, making up more than half of all visible matter. Neutron scattering provides information about the positions, motions, and magnetic properties of solids. When a beam of neutrons is aimed at a sample, many neutrons will pass through the material. But some will interact directly with atomic nuclei and "bounce" away at an angle, like colliding balls in a game of pool. This behavior is called neutron diffraction, or neutron scattering. Using detectors, scientists can count scattered neutrons, measure their energies and the angles at which they scatter, and map their final position

137

Neutron Diffraction Studies of a Class A beta-Lactamase Toho-1 E166A/R274N/R276N Triple Mutant  

SciTech Connect

beta-Lactam antibiotics have been used effectively over several decades against many types of bacterial infectious diseases. However, the most common cause of resistance to the beta-lactam antibiotics is the production of beta-lactamase enzymes that inactivate beta-lactams by rapidly hydrolyzing the amide group of the beta-lactam ring. Specifically, the class A extended-spectrum beta-lactamases (ESBLs) and inhibitor-resistant enzymes arose that were capable of hydrolyzing penicillins and the expanded-spectrum cephalosporins and monobactams in resistant bacteria, which lead to treatment problems in many clinical settings. A more complete understanding of the mechanism of catalysis of these ESBL enzymes will impact current antibiotic drug discovery efforts. Here, we describe the neutron structure of the class A, CTX-M-type ESBL Toho-1 E166A/R274N/R276N triple mutant in its apo form, which is the first reported neutron structure of a beta-lactamase enzyme. This neutron structure clearly reveals the active-site protonation states and hydrogen-bonding network of the apo Toho-1 ESBL prior to substrate binding and subsequent acylation. The protonation states of the active-site residues Ser70, Lys73, Ser130, and Lys234 in this neutron structure are consistent with the prediction of a proton transfer pathway from Lys73 to Ser130 that is likely dependent on the conformation of Lys73, which has been hypothesized to be coupled to the protonation state of Glu166 during the acylation reaction. Thus, this neutron structure is in agreement with a proposed mechanism for acylation that identifies Glu166 as the general base for catalysis.

Blakeley, Matthew P. [Institut Laue-Langevin (ILL); Chen, Yu [ORNL; Afonine, Pavel [Lawrence Berkeley National Laboratory (LBNL)

2010-01-01T23:59:59.000Z

138

X-ray diffraction study of zirconia pillared clays  

Science Journals Connector (OSTI)

X-ray powder diffraction (XRPD) and X-ray radial electronic distribution density (RED) of initial and zirconia-pillared interlayered clays (Zr-PILC) were studied. After pillaring, the basal ... under air to 17.7 ...

D.A. Zyuzin; E.M. Moroz; T.G. Kuznetsova

2004-01-01T23:59:59.000Z

139

Coherence lengths and neutron optics  

Science Journals Connector (OSTI)

The dynamical diffraction of divergent beams and its application to neutron interferometry are considered. The coherence properties of thermal neutrons are studied, and it is shown that the extreme anisotropy of dynamically diffracted wave packets should be included in the discussion of coherence lengths. Finally, the mechanism leading to a nondispersive phase shift is investigated.

D. Petrascheck

1987-05-01T23:59:59.000Z

140

Pressure dependent diffraction and spectroscopy of a dimerized antiferromagnet  

SciTech Connect

We present pressure dependent neutron diffraction and inelastic neutron scattering measurements of the dimerized antiferromagnet Ba$_3$Mn$_2$O$_8$. The room temperature diffraction measurements reveal a linear decrease in lattice constant as a function of applied pressure. No structural transitions are observed. The low-temperature neutron spectroscopy measurements indicate a small change in magnetic scattering intensity in the vicinity of the spin gap for pressures up to $P=0.6$~kbar.

Stone, Matthew B [ORNL; Tulk, Christopher A [ORNL; dos Santos, Antonio M. [Oak Ridge National Laboratory (ORNL); Molaison, Jamie J [ORNL; Chang, S. [Ames Laboratory; Leo, J B [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Samulon, Eric C [Stanford University; Shapiro, Max C [Stanford University; Fisher, Ian R [Stanford University

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

X-ray Diffraction Laboratory: Department of Chemistry Texas A & M University  

E-Print Network (OSTI)

X-ray Diffraction Laboratory: Department of Chemistry Texas A & M University Doc. No: SOPPOWGAD data collection on the Bruker GADDS Powder X-ray Diffractometer. POLICY: Data must be collected AND PRECAUTIONS 1. Powder X-ray diffraction is a method by which investigators can identify the materials

Meagher, Mary

142

Dr. Ashfia Huq | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Ashfia Huq Ashfia Huq Dr. Ashfia Huq Instrument Scientist: POWGEN Education PhD in Physics, Stony Brook University, in Stony Brook, New York (May 2003) AB degree, Magna Cum Laude with majors in Physics and Computer Science, Mount Holyoke College, South Hadley, Massachusetts (May 1996) Description of Research My primary research interest is neutron and X-ray powder diffraction of condensed matter systems and materials for energy storage. Topics include battery materials, solid oxide fuel cell (SOFC) materials, hydrogen storage materials, catalysis, and magnetic and structural properties of strongly correlated electron systems such as geometrically frustrated magnets, superconductors, etc. Selected Publications Zhonghe Bi, Juan Pena-Martinez, Jung-Hyun Kim, Craig A. Bridges, Ashfia

143

Multiple feed powder splitter  

DOE Patents (OSTI)

A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

Lewis, Gary K. (Los Alamos, NM); Less, Richard M. (Los Alamos, NM)

2001-01-01T23:59:59.000Z

144

Multiple feed powder splitter  

DOE Patents (OSTI)

A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

Lewis, Gary K. (Los Alamos, NM); Less, Richard M. (Los Alamos, NM)

2002-01-01T23:59:59.000Z

145

Definition: X-Ray Diffraction (XRD) | Open Energy Information  

Open Energy Info (EERE)

X-Ray Diffraction (XRD) X-Ray Diffraction (XRD) Jump to: navigation, search Dictionary.png X-Ray Diffraction (XRD) X-Ray Diffraction (XRD) is a laboratory-based technique commonly used for identification of crystalline materials and analysis of unit cell dimensions. One of two primary types of XRD analysis (X-ray powder diffraction and single-crystal XRD) is commonly applied to samples to obtain specific information about the crystalline material under investigation. X-ray powder diffraction is widely used in geology, environmental science, material science, and engineering to rapidly identify unknown crystalline substances (typically in less than 20 minutes). A pure, finely ground, and homogenized sample is required for determination of the bulk composition. Additional uses include detailed

146

Neutron Activation Analysis for the Demonstration of Amphibolite Rock-Weathering Activity of a Yeast  

Science Journals Connector (OSTI)

...research-article General Microbial Ecology Neutron Activation Analysis for the Demonstration...University of Kiel, Kiel, Germany Neutron activation analysis was employed in a...demonstrated by comparing a spectrum of neutron-activated amphibolite powder (particle...

E. Rades-Rohkohl; P. Hirsch; O. Frnzle

1979-12-01T23:59:59.000Z

147

Development of heavy mineral and heavy element database of soil sediments in Japan using synchrotron radiation X-ray powder diffraction and high-energy (116keV) X-ray fluorescence analysis: 1. Case study of Kofu and Chiba region  

Science Journals Connector (OSTI)

We have started the construction of a nationwide forensic soil sediment database for Japan based on the heavy mineral and trace heavy element compositions of stream sediments collected at 3024 points all over Japan obtained by high-resolution synchrotron X-ray powder diffraction (SR-XRD) and high-energy synchrotron X-ray fluorescence analysis (HE-SR-XRF). In this study, the performance of both techniques was demonstrated by analyzing soil sediments from two different geological regions, the Kofu and Chiba regions in Kanto province, to construct database that can be applied in the future to provenance analysis of soil evidence from a crime scene. The sediments from the quaternary volcanic lithology of the Chiba region were found to be dominated by heavy minerals of volcanic origin orthopyroxene, clinopyroxene, and amphibole, and the \\{REEs\\} (rare earth elements) within the region showed similar geochemical behavior. On the other hand, four distinct heavy mineral groups were identified in the sediments of the Kofu region, where there is a great variety of underlying bedrock, and the geochemical behavior of the \\{REEs\\} in the sediments also varied accordingly to their geological origins. As such, our study shows that high-resolution SR-XRD data can provide information on the spatial distribution patterns of heavy minerals in stream sediments, playing an important role in determining their likely geographical origin. Meanwhile, the highly sensitive HE-SR-XRF data allow us to study the geochemical behavior of trace heavy elements, especially the \\{REEs\\} in the sediments, providing additional support to further constrain the likely geographical origin of the sediments determined by heavy minerals.

Willy Shun Kai Bong; Izumi Nakai; Shunsuke Furuya; Hiroko Suzuki; Yoshinari Abe; Keiichi Osaka; Takuya Matsumoto; Masayoshi Itou; Noboru Imai; Toshio Ninomiya

2012-01-01T23:59:59.000Z

148

High-Pressure and High-Temperature Powder Diffraction  

Science Journals Connector (OSTI)

...pressure and varies the motor speed is often used...12.398 is from the quantum mechanical relationship...detectors could in the future reduce data collection...kind of studies in the future. Other more fundamental...addressed in the near future. Temperature gradients...

Yingwei Fei; Yanbin Wang

149

JOURNAL DE PHYSIQUE CoZZoque C8, suppZe'ment au n08, Tome 41, aoGt 1980, page C8-156 NEUTRON DIFFRACTION BY LIQUID SEGREGATED COPPER-LEAD ALLOYS  

E-Print Network (OSTI)

38401 Saint Martin drH2res, France. Abstract.- Neutron scattering experiments were performed on liquid corre- .20 is the scattering angle, X the neutron wave- si: 'the modulus of the scatte-lations betweenJOURNAL DE PHYSIQUE CoZZoque C8, suppZe'ment au n08, Tome 41, aoGt 1980, page C8-156 NEUTRON

Boyer, Edmond

150

Concepts of Neutron ScatteringConcepts of Neutron Scattering 66thth PSI Summer School on Condensed Matter ResearchPSI Summer School on Condensed Matter Research  

E-Print Network (OSTI)

Concepts of Neutron ScatteringConcepts of Neutron Scattering 66thth PSI Summer School on Condensed Andrew Boothroyd University of Oxford Basic features of neutron scattering Neutron diffraction Neutron on the lattice * * * #12;ScatteringScattering ``nuts and boltsnuts and bolts'' Neutrons, photons, electrons

Boothroyd, Andrew

151

Aqueous Solutions and Neutron Scattering  

Science Journals Connector (OSTI)

The application of neutron diffraction techniques to aqueous solutions is described, and a framework involving the use of isotopic substitution is set up to illustrate the scope of the method. Specific applications described include a study of glassy ...

G. W. Neilson; J. E. Enderby

1996-01-25T23:59:59.000Z

152

Ultrafine hydrogen storage powders  

DOE Patents (OSTI)

A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

Anderson, Iver E. (Ames, IA); Ellis, Timothy W. (Doylestown, PA); Pecharsky, Vitalij K. (Ames, IA); Ting, Jason (Ames, IA); Terpstra, Robert (Ames, IA); Bowman, Robert C. (La Mesa, CA); Witham, Charles K. (Pasadena, CA); Fultz, Brent T. (Pasadena, CA); Bugga, Ratnakumar V. (Arcadia, CA)

2000-06-13T23:59:59.000Z

153

Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering.  

E-Print Network (OSTI)

?? The diffusive motions of the Brnsted superacid, hydrogen fluoride, have been studied using quasielastic neutron scattering. Neutron and high energy X-ray diffraction measurements on (more)

Molaison, Jamie John

2006-01-01T23:59:59.000Z

154

2011 U.S. National School on Neutron and X-ray Scattering  

SciTech Connect

The 13th annual U.S. National School on Neutron and X-ray Scattering was held June 11 to 25, 2011, at both Oak Ridge and Argonne National Laboratories. This school brought together 65 early career graduate students from 56 different universities in the US and provided them with a broad introduction to the techniques available at the major large-scale neutron and synchrotron x-ray facilities. This school is focused primarily on techniques relevant to the physical sciences, but also touches on cross-disciplinary bio-related scattering measurements. During the school, students received lectures by over 30 researchers from academia, industry, and national laboratories and participated in a number of short demonstration experiments at Argonne's Advanced Photon Source (APS) and Oak Ridge's Spallation neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to get hands-on experience in using neutron and synchrotron sources. The first week of this year's school was held at Oak Ridge National Lab, where Lab director Thom Mason welcomed the students and provided a shitorical perspective of the neutron and x-ray facilities both at Oak Ridge and Argonne. The first few days of the school were dedicated to lectures laying out the basics of scattering theory and the differences and complementarity between the neutron and x-ray probes given by Sunil Sinha. Jack Carpenter provided an introduction into how neutrons are generated and detected. After this basic introduction, the students received lectures each morning on specific techniques and conducted demonstration experiments each afternoon on one of 15 different instruments at either the SNS or HFIR. Some of the topics covered during this week of the school included inelastic neutron scattering by Bruce Gaulin, x-ray and neutron reflectivity by Chuck Majkrazak, small-angle scattering by Volker Urban, powder diffraction by Ashfia Huq and diffuse scattering by Gene Ice.

Lang, Jonathan [Argonne National Laboratory (ANL); te Vethuis, Suzanne [Argonne National Laboratory (ANL); Ekkebus, Allen E [ORNL; Chakoumakos, Bryan C [ORNL; Budai, John D [ORNL

2012-01-01T23:59:59.000Z

155

Iowa Powder Atomization Technologies  

SciTech Connect

The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

None

2012-01-01T23:59:59.000Z

156

Previously, DC Magnets located at Neutron-Scattering Beamlines were commercially-manufactured superconducting magnets and limited to 17 T. A  

E-Print Network (OSTI)

Previously, DC Magnets located at Neutron-Scattering Beamlines were commercially, this was the first designed specifically for neutron scattering and the first to include resistive suitable for neutron scattering, diffraction and spectroscopy experiments with the neutron beam passing

Weston, Ken

157

X-Ray Diffraction (XRD) | Open Energy Information  

Open Energy Info (EERE)

X-Ray Diffraction (XRD) X-Ray Diffraction (XRD) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: X-Ray Diffraction (XRD) Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Lab Analysis Techniques Exploration Sub Group: Rock Lab Analysis Parent Exploration Technique: Rock Lab Analysis Information Provided by Technique Lithology: Rapid and unambiguous identification of unknown minerals.[1] Stratigraphic/Structural: Hydrological: Thermal: Dictionary.png X-Ray Diffraction (XRD): X-Ray Diffraction (XRD) is a laboratory-based technique commonly used for identification of crystalline materials and analysis of unit cell dimensions. One of two primary types of XRD analysis (X-ray powder diffraction and single-crystal XRD) is commonly applied to samples to

158

Portable X-Ray Diffraction (XRD) | Open Energy Information  

Open Energy Info (EERE)

Portable X-Ray Diffraction (XRD) Portable X-Ray Diffraction (XRD) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Portable X-Ray Diffraction (XRD) Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Field Techniques Exploration Sub Group: Data Collection and Mapping Parent Exploration Technique: Data Collection and Mapping Information Provided by Technique Lithology: Rapid and unambiguous identification of unknown minerals.[1] Stratigraphic/Structural: Hydrological: Thermal: Dictionary.png Portable X-Ray Diffraction (XRD): Portable X-Ray Diffraction (XRD) is a field-based technique that can be used for identification of crystalline materials and analysis of unit cell dimensions. Portable XRD analysis is similar to X-ray powder diffraction,

159

Publications from Research Conducted at WAND | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Publications from Research Conducted at WAND Publications from Research Conducted at WAND 2013 Publications Durand A. M., Belanger D. P., Booth C. H., Ye F., Chi S., Fernandez-Baca J. A., Bhat M., "Magnetism and phase transitions in LaCoO3", Journal of Physics: Condensed Matter 25, 382203 (2013). Kobayashi R., Kaneko K., Wakimoto S., Chi S., Sanada N., Watanuki R., Suzuki K., "Powder neutron diffraction study of HoCoGa", Journal of the Korean Physical Society 63, 337-340 (2013). Retuerto M., Li M. R., Ignatov A., Croft M., Ramanujachary K. V., Chi S., Hodges J. P., Dachraoui W., Hadermann J., Tran T. T., Halasyamani P. S., Grams C. P., Hemberger J., Greenblatt M., "Polar and magnetic layered A-site and rock salt B-site-ordered NaLnFeWO6 (Ln = La, Nd) perovskites", Inorganic Chemistry 52, 12482-12491 (2013).

160

Elastic scattering research at a 1 MW long pulse spallation neutron source  

SciTech Connect

The elastic scattering working group investigated instrumentation for powder diffraction, single-crystal diffraction, small-angle diffraction, and reflectometry. For this purpose, three subgroups were formed; one for powder diffraction and single-crystal diffraction, one for small-angle diffraction, and one for reflectometry. For the most part these subgroups worked separately, but for part of the time the reflectometry and small-angle diffraction subgroups met together to discuss areas of common interest. Contributors in each of these subgroups are indicated below along with the discussion of these subgroup deliberations.

Crawford, R.K.

1995-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Method to blend separator powders  

DOE Patents (OSTI)

A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

Guidotti, Ronald A. (Albuquerque, NM); Andazola, Arthur H. (Albuquerque, NM); Reinhardt, Frederick W. (Albuquerque, NM)

2007-12-04T23:59:59.000Z

162

Powder transport model for laser cladding by lateral powder feeding: I. Powder flow field with cylindrical distribution  

Science Journals Connector (OSTI)

Powder transport ratio is defined as the mass ratio of powder particles fed into the molten pool to all powders transported in the process of laser cladding by lateral powder feeding. According to the...

Xinyong Gong; Yongzhong Zhang; Mingkun Liu

2013-08-01T23:59:59.000Z

163

Kinetics of alloy formation at the interfaces in a Ni-Ti multilayer: X-ray and neutron reflectometry study  

Science Journals Connector (OSTI)

Vacuum-deposited Ni/Ti multilayers on annealing at different temperatures exhibit formation of ordered alloy layers at interfaces. We have studied in detail the formation of alloy at interfaces of a Ni/Ti multilayer on annealing at 300?C and 400?C using powder x-ray diffraction, x-ray reflectometry, polarized neutron reflectometry, and off-specular x-ray reflectometry techniques. Correlation among structural, magnetic, and morphological properties in as-deposited Ni/Ti multilayer as well as in a sample annealed at 300?C and 400?C has been studied. X-ray diffraction technique was used to obtain crystal structure of the sample. Specular x-ray reflectometry and neutron reflectometry were used to determine the growth of alloy layers from density profile, as a function of depth in the sample. From off-specular x-ray reflectivity we found that the in-plane correlation lengths at the interfaces grew with annealing. This is associated with alloy crystallite growth obtained from x-ray reflectometry. Detailed magnetic-moment density profile of as-deposited as well as annealed multilayer sample has been determined by polarized neutron reflectometry measurements, which was used to determine the magnetic nature of the alloy layers. The results show formation of nonmagnetic alloy layers at the interfaces on annealing. From the Bragg-peak intensities of x-ray reflectivity and polarized neutron reflectivity measurements, we have estimated the diffusion lengths after annealing at 300?C and 400?C.

Surendra Singh; Saibal Basu; Pramod Bhatt; A. K. Poswal

2009-05-28T23:59:59.000Z

164

Diffraction-Based Density Restraints for Membrane and Membrane-Peptide Molecular Dynamics Simulations  

E-Print Network (OSTI)

or neutron scattering-length density projected along the bilayer normal (5). These profiles represent, California; and z NIST Center for Neutron Research, National Institute of Standards and Technology. INTRODUCTION X-ray and neutron diffraction are commonly used for studying the structure of membrane systems (1

White, Stephen

165

Neutron-Neutron Interaction  

Science Journals Connector (OSTI)

The present status of the problem of charge dependence is discussed. The information about the neutron-neutron interaction derived from the two-neutron system, three-nucleon systems, final-state interactions in multiparticle reactions, and peripheral processes is critically evaluated. The experimental data indicate the breakdown of charge independence by about 3-5%. Evidence concerning the violation of charge symmetry is inconclusive, but it seems that most of the data are consistent with the assumption that charge symmetry is satisfied within 0.5-1%. The most suitable studies which might improve the knowledge of the neutron-neutron forces are indicated.

IVO LAUS

1967-07-01T23:59:59.000Z

166

X-ray Diffraction Laboratory: Department of Chemistry Texas A & M University  

E-Print Network (OSTI)

X-ray Diffraction Laboratory: Department of Chemistry Texas A & M University Doc. No: SOPPOWD8 Standard Operating Procedure Title: X-ray Powder Diffraction: D8 Advanced Rev No: Issue date: 1.001 12/29/2008 Page: 1 of 3 SOP: SOPPOWD8 Last date revised: December 23 2009 Date approved: December 29 2009 X-ray

Meagher, Mary

167

Diffractive parton density functions  

E-Print Network (OSTI)

We discuss the perturbative QCD description of diffractive deep-inelastic scattering, and extract diffractive parton distributions from recent HERA data. The asymptotic collinear factorisation theorem has important modifications in the sub-asymptotic HERA regime. In addition to the usual resolved Pomeron contribution, the direct interaction of the Pomeron must also be accounted for. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation, analogous to the parton distributions of the photon.

Watt, G

2005-01-01T23:59:59.000Z

168

Diffractive parton density functions  

E-Print Network (OSTI)

We discuss the perturbative QCD description of diffractive deep-inelastic scattering, and extract diffractive parton distributions from recent HERA data. The asymptotic collinear factorisation theorem has important modifications in the sub-asymptotic HERA regime. In addition to the usual resolved Pomeron contribution, the direct interaction of the Pomeron must also be accounted for. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation, analogous to the parton distributions of the photon.

G. Watt

2005-11-29T23:59:59.000Z

169

Diffractive deep inelastic scattering  

SciTech Connect

A new approach to the analysis of diffractive deep inelastic data is presented. We show that the collinear factorisation theorem, which holds for diffractive DIS, has important modifications in the sub-asymptotic HERA regime, which can be quantified by using perturbative QCD. In fact the diffractive parton densities are shown to satisfy an inhomogeneous evolution equation. Moreover it is necessary to include both the gluonic and sea-quark t-channel components of the perturbative Pomeron.

Martin, A.D.; Ryskin, M.G. [IPPP, Physics Department, University of Durham, DH1 3LE (United Kingdom); Watt, G. [DESY, 22607 Hamburg (Germany)

2005-10-06T23:59:59.000Z

170

Three-dimensional boron particle loaded thermal neutron detector  

DOE Patents (OSTI)

Three-dimensional boron particle loaded thermal neutron detectors utilize neutron sensitive conversion materials in the form of nano-powders and micro-sized particles, as opposed to thin films, suspensions, paraffin, etc. More specifically, methods to infiltrate, intersperse and embed the neutron nano-powders to form two-dimensional and/or three-dimensional charge sensitive platforms are specified. The use of nano-powders enables conformal contact with the entire charge-collecting structure regardless of its shape or configuration.

Nikolic, Rebecca J.; Conway, Adam M.; Graff, Robert T.; Kuntz, Joshua D.; Reinhardt, Catherine; Voss, Lars F.; Cheung, Chin Li; Heineck, Daniel

2014-09-09T23:59:59.000Z

171

EMSL - Spectroscopy and Diffraction  

NLE Websites -- All DOE Office Websites (Extended Search)

loss spectroscopy and electron backscatter diffraction Local Electrode Atom Probe tomography system with 355 nm UV laser and reflectron flight path for high mass resolution...

172

Characterization of Cu{sub 6}Sn{sub 5} intermetallic powders produced by water atomization and powder heat treatment  

SciTech Connect

Since the Cu{sub 6}Sn{sub 5} intermetallic shows its importance in industrial applications, the Cu{sub 6}Sn{sub 5} intermetallic-containing powders, produced by a powder processing route with a high production rate, were characterized. The route consisted of water atomization of an alloy melt (Cu61 wt.% Sn) and subsequent heat treatment of the water-atomized powders. Characterization of the water-atomized powders and their heated forms was conducted by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Fine water-atomized powder microstructures consisted of primary hexagonal ?-Cu{sub 6.25}Sn{sub 5} dendrites coexisting with interdendritic ?-Cu{sub 6.25}Sn{sub 5} + ?-Sn eutectic. Solidification of fine melt droplets was governed by surface nucleation and growth of the primary hexagonal ?-Cu{sub 6.25}Sn{sub 5} dendrites followed by ?-Cu{sub 6.25}Sn{sub 5} + ?-Sn eutectic solidification of the remnant liquid. In coarse melt droplets, nucleation and growth of primary ?-Cu{sub 3}Sn dendrites were followed by peritectic reaction (?-Cu{sub 3}Sn + liquid ? ?-Cu{sub 6.25}Sn{sub 5}) or direct crystallization of ?-Cu{sub 6.25}Sn{sub 5} phase from the undercooled melt. Finally, the ?-Cu{sub 6.25}Sn{sub 5} + ?-Sn eutectic solidification of the remnant liquid occurred. Heating of the water-atomized powders at different temperatures resulted in microstructural homogenization. The water-atomized powders with mixed phases were transformed to powders with single monoclinic ?-Cu{sub 6}Sn{sub 5} phase. - Highlights: The Cu{sub 6}Sn{sub 5} intermetallic powder production route was proposed. Single phase Cu{sub 6}Sn{sub 5} powders could be by water atomization and heating. Water-atomized CuSn powders contained mixed CuSn phases. Solidification and heat treatment of water-atomized CuSn powders are explained.

Tongsri, Ruangdaj, E-mail: ruangdt@mtec.or.th [Powder Metallurgy Research and Development Unit (PM-RDU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Yotkaew, Thanyaporn, E-mail: thanyy@mtec.or.th [Powder Metallurgy Research and Development Unit (PM-RDU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Krataitong, Rungtip, E-mail: rungtipk@mtec.or.th [Powder Metallurgy Research and Development Unit (PM-RDU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Wila, Pongsak, E-mail: pongsakw@mtec.or.th [Powder Metallurgy Research and Development Unit (PM-RDU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Sir-on, Autcharaporn, E-mail: autchars@mtec.or.th [Materials Characterization Research Unit (MCRU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Muthitamongkol, Pennapa, E-mail: pennapm@mtec.or.th [Materials Characterization Research Unit (MCRU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand); Tosangthum, Nattaya, E-mail: nattayt@mtec.or.th [Powder Metallurgy Research and Development Unit (PM-RDU), National Metal and Materials Technology Center, 114 Paholyothin, Klong 1, Klong Luang, Pathum Thani 12120 (Thailand)

2013-12-15T23:59:59.000Z

173

Neutron macromolecular crystallography with LADI-III  

Science Journals Connector (OSTI)

The LADI-III instrument for measuring neutron macromolecular crystallography diffraction data is described. The data collection of type-III perdeuterated antifreeze protein is given as an example.

Blakeley, M.P.

2010-10-20T23:59:59.000Z

174

X-Ray Diffraction on NIF  

SciTech Connect

The National Ignition Facility (NIF) is currently a 192 beam, 1.6 MJ laser. NIF Ramp-Compression Experiments have already made the relevant exo-planet pressure range from 1 to 50 Mbar accessible. We Proposed to Study Carbon Phases by X-Ray Diffraction on NIF. Just a few years ago, ultra-high pressure phase diagrams for materials were very 'simple'. New experiments and theories point out surprising and decidedly complex behavior at the highest pressures considered. High pressures phases of aluminum are also predicted to be complex. Recent metadynamics survey of carbon proposed a dynamic pathway among multiple phases. We need to develop diagnostics and techniques to explore this new regime of highly compressed matter science. X-Ray Diffraction - Understand the phase diagram/EOS/strength/texture of materials to 10's of Mbar. Strategy and physics goals: (1) Powder diffraction; (2) Begin with diamond; (3) Continue with metals etc.; (4) Explore phase diagrams; (5) Develop liquid diffraction; and (6) Reduce background/improve resolution.

Eggert, J H; Wark, J

2012-02-15T23:59:59.000Z

175

Structure and Dynamics of Cholesterol-Containing Polyunsaturated Lipid Membranes Studied by Neutron  

E-Print Network (OSTI)

Structure and Dynamics of Cholesterol-Containing Polyunsaturated Lipid Membranes Studied by Neutron by neutron diffraction, 2 H-NMR and 13 C-MAS NMR. Scattering length distribution func- tions of cholesterol Phosphatidylcholine Á Membrane Á Cholesterol Á Neutron diffraction Á NMR Introduction The lipid bilayer of cell

White, Stephen

176

Multilayer dielectric diffraction gratings  

DOE Patents (OSTI)

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Perry, Michael D. (Livermore, CA); Britten, Jerald A. (Oakley, CA); Nguyen, Hoang T. (Livermore, CA); Boyd, Robert (Livermore, CA); Shore, Bruce W. (Livermore, CA)

1999-01-01T23:59:59.000Z

177

Multilayer dielectric diffraction gratings  

DOE Patents (OSTI)

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

1999-05-25T23:59:59.000Z

178

Definition: Portable X-Ray Diffraction (XRD) | Open Energy Information  

Open Energy Info (EERE)

Definition Definition Edit with form History Facebook icon Twitter icon » Definition: Portable X-Ray Diffraction (XRD) Jump to: navigation, search Dictionary.png Portable X-Ray Diffraction (XRD) Portable X-Ray Diffraction (XRD) is a field-based technique that can be used for identification of crystalline materials and analysis of unit cell dimensions. Portable XRD analysis is similar to X-ray powder diffraction, which has traditionally been used in geology, environmental science, material science, and engineering to rapidly identify unknown crystalline substances. Portable XRD analysis allows for simpler sample preparation, faster analytical times than traditional methods (less than 2 minutes), and can be performed at the sampling site in the field. A pure, finely ground

179

Preparation of superconductor precursor powders  

DOE Patents (OSTI)

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

Bhattacharya, Raghunath (Littleton, CO); Blaugher, Richard D. (Evergreen, CO)

1995-01-01T23:59:59.000Z

180

Neutron Polarimetry  

Science Journals Connector (OSTI)

8 July 1993 research-article Neutron Polarimetry P. Jane Brown J. Bruce Forsyth Francis Tasset Zero-field neutron polarimetry is a technique which has...polarization analysis to be carried out in a neutron scattering experiment. The incident...

1993-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents (OSTI)

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1996-01-01T23:59:59.000Z

182

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents (OSTI)

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

1996-01-02T23:59:59.000Z

183

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents (OSTI)

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1995-01-01T23:59:59.000Z

184

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents (OSTI)

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2 /g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1994-01-01T23:59:59.000Z

185

Neutron scattering study on f-electron states in PrCu4Au  

SciTech Connect

Neutron scattering studies were carried out for investigating heavy-electron-like behaviors of PrCu4Au. Excitation spectra are composed of crystal-field (CF) excitations in the Pr3+4f2 electron configuration and a broad component. The CF splitting ground state is a triplet 5. The type-II antiferromagnetic ordering characterized by the propagation vector (1/2, 1/2, 1/2) appears below approximately 4 K. The powder diffraction pattern is reproduced by the ordered magnetic moments aligning along the direction perpendicular to the propagation vector. The magnitude of the ordered magnetic moment is evaluated as 1.36uB/Pr, which is less than 2.0uB/Pr expected from the 5 ground state. Dual electronic states of both localized and itinerant character are inferred.

Iwasa, Kazuaki [Tohoku University, Japan; Kobayashi, Hiroki [Tohoku University, Japan; Saito, Kotaro [Tohoku University, Japan; Tomiyasu, Dr. Keisuke [Tohoku University, Japan; Zhang, Shuai [Hiroshima University, Japan; Isikawa, Yosikazu [Toyama University, Japan; Mignot, Jean-Michel [Laboratoire Leon Brillouin, France; Andre, G. [Laboratoire Leon Brillouin, France; Kawana, Kaichi [KEK, Tsukuba, Ibaraki, Japan; Kolesnikov, Alexander I [ORNL; Savici, Andrei T [ORNL; Granroth, Garrett E [ORNL

2014-01-01T23:59:59.000Z

186

Rotary powder feed through apparatus  

DOE Patents (OSTI)

A device for increasing the uniformity of solids within a solids fabrication system, such as a direct light fabrication (DLF) system in which gas entrained powders are passed through the focal point of a moving high-power light which fuses the particles in the powder to a surface being built up in layers. The invention provides a feed through interface wherein gas entrained powders input from stationary input lines are coupled to a rotating head of the fabrication system. The invention eliminates the need to provide additional slack in the feed lines to accommodate head rotation, and therefore reduces feed line bending movements which induce non-uniform feeding of gas entrained powder to a rotating head.

Lewis, Gary K. (Los Alamos, NM); Less, Richard M. (Los Alamos, NM)

2001-01-01T23:59:59.000Z

187

EMSL: Capabilities: Spectroscopy and Diffraction  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy and Diffraction Spectroscopy and Diffraction Additional Information Meet the Spectroscopy and Diffraction Experts Related EMSL User Projects Spectroscopy and Diffraction Tools are Applied to all Science Themes Tutorial: XPS Tools for Surface Analysis Spectroscopy and Diffraction brochure EMSL's suite of spectroscopy and diffraction instruments allows users to study solid-, liquid-, and gas-phase sample structure and composition with remarkable resolution. Ideal for integrated studies, spectrometers and diffractometers are easily coupled with EMSL's computational and modeling capabilities, allowing users to apply a multifaceted research approach for experimental data interpretation and gain fundamental understanding of scientific problems. At EMSL, spectroscopy and diffraction instruments are

188

Neutron Production, Neutron Facilities and Neutron Instrumentation  

Science Journals Connector (OSTI)

...Mexico, 87545, U.S.A, e-mail: sven@lanl.gov Hans-Georg Priesmeyer Geesthacht Neutron Scattering Facility, GKSS Research Center, 21502 Geesthacht, Germany, e-mail: hans-georg.priesmeyer@gkss.de NEUTRON GENERATION The...

Sven C. Vogel; Hans-Georg Priesmeyer

189

A neutron crystallographic analysis of a rubredoxin mutant at 1.6 ? resolution  

Science Journals Connector (OSTI)

A single-crystal neutron diffraction study has been carried out at 1.6 ? resolution on a mutant rubredoxin from the hyperthermophilic archeon P. furiosus.

Chatake, T.

2004-07-21T23:59:59.000Z

190

Neutron Reflectivity  

Science Journals Connector (OSTI)

Neutron Reflectivity ... This article is part of the Neutron Reflectivity special issue. ... The articles in this special issue on neutron reflectivity cover a broad range of the applications of this technique and the related X-ray and neutron scattering experiments of SAXS, SANS, GISAXS, and GISANS. ...

Jeffrey Penfold

2009-03-31T23:59:59.000Z

191

Colored diffraction catastrophes  

Science Journals Connector (OSTI)

...geometrically achromatic. In our bathroom-window glass ex- periments it was easy to achieve this by selecting the central P2C _ U~~~~~~~~~ TX FIG. 7. Arrangement for observing colored diffraction catastro- phes. C, camera; G, glass; L...

M V Berry; S Klein

1996-01-01T23:59:59.000Z

192

About Neutrons  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Basics Neutron Basics A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter. Find Out What a Neutron Is Youtube icon Properties of Neutrons How Can Neutrons Be Used for Research? Image of glucose movement in plants Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel. Neutrons have many properties that make them ideal for certain types of

193

X-ray and neutron diffraction study of the defect crystal structure of the as-grown nonstoichiometric phase Y{sub 0.715}Ca{sub 0.285}F{sub 2.715}  

SciTech Connect

This work begins a series of papers aimed at studying the defect structure of nonstoichiometric phases R{sub 1-y}Ca{sub y}F{sub 3-y} with a tysonite-type (LaF{sub 3}) structure. In the single-crystal structure of Y{sub 0.715}Ca{sub 0.285}F{sub 2.715} with a tysonite-type small unit cell (sp. gr. P6{sub 3}/mmc, a = 3.9095(2) A, c = 6.9829(2) A; Z = 2; R{sub w} = 2.16%), the displacements of Y{sup 3+} cations and F{sup 2-} anions from 6{sub 3} symmetry axes were observed for the first time. The X-ray diffraction pattern shows weak satellites insufficient for structural calculations. The LaF{sub 3} structure type is stabilized up and down on the temperature scale due to anion vacancies and the symmetrizing effect of Ca{sup 2+} cations lying on 6{sub 3} symmetry axes. At 120 Degree-Sign C the fluoride-ion conductivity in the nonstoichiometric phase Y{sub 0.715}Ca{sub 0.285}F{sub 2.715} is five orders of magnitude higher than that in the stoichiometric phase {beta}-YF{sub 3}. The transition to a superionic state is caused by a deviation from stoichiometry and is not associated with reconstructive phase transformation.

Bolotina, N. B., E-mail: bolotina@ns.crys.ras.ru; Kalyukanov, A. I.; Chernaya, T. S.; Verin, I. A.; Buchinskaya, I. I.; Sorokin, N. I.; Sobolev, B. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2013-07-15T23:59:59.000Z

194

Novel hollow powder porous structures  

SciTech Connect

Recent finite element calculations indicate that structures constructed from partially compacted hollow spheres exhibit a greater stiffness and strength than many other cellular structures at comparable density. It has been observed that gas atomization of metallic powders often leads to entrapment of the flow field gas. The resulting hollow powders are an unwanted by-product in the sense that they lead to porosity and future sites of defect in solid parts. Here a method is developed to separate the hollow powders according to their size, shape and density. They are then consolidated to a porous structure. Examples of this are given for both a titanium alloy and a nickel-base superalloy. The compressive mechanical properties are measured and compared to those of other porous structures.

Sypeck, D.J.; Parrish, P.A.; Wadley, H.N.G. [Univ. of Virginia, Charlottesville, VA (United States). School of Engineering and Applied Science

1998-12-31T23:59:59.000Z

195

Neutron scattering, a powerful tool to study clay minerals  

Science Journals Connector (OSTI)

Abstract Of the techniques used to study clay minerals, neutron scattering has become more familiar to clay scientists over the past decade. A brief account of neutron scattering theory is given in this review, followed by a description of measurements that can be made using neutron diffraction and neutron scattering spectroscopy, and especially quasi-elastic neutron scattering. Then recent examples of the application of neutron scattering methods to the study of clay minerals are presented, and finally the potential advantages of such experimental results when combined to molecular dynamics are discussed. To conclude, the potential perspectives that the European Spallation Source brings to this subject are pointed out.

Murillo L. Martins; Will P. Gates; Laurent Michot; Eric Ferrage; Virginie Marry; Heloisa N. Bordallo

2014-01-01T23:59:59.000Z

196

Neutron-Neutron Scattering Length  

Science Journals Connector (OSTI)

The final-state interaction of the two neutrons from the reaction ?-+d?2n+? has a pronounced and distinctive effect on the momentum spectrum of the outgoing particles. In particular, the neutron spectrum is sharply peaked in the neighborhood of 2 Mev, with a shape that is quite sensitive to the strength of the nn interaction. In the region of this peak, the relative neutron-neutron momentum is so small that the nn interaction is completely characterized by its scattering length. Hence it is proposed that a measurement of the shape of the neutron spectrum from this reaction may provide a convenient means of measuring the neutron-neutron scattering length. Neutron spectra are calculated in an impulse approximation, for several assumed values of the scattering length. It appears from their shapes that, in this way, present neutron-detection techniques should be capable of determining the scattering length to within 25%.

Kirk W. McVoy

1961-03-01T23:59:59.000Z

197

Neutron skins and neutron stars  

SciTech Connect

The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ('PREX') at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in {sup 208}Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.

Piekarewicz, J. [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States)

2013-11-07T23:59:59.000Z

198

Awards 2007 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

7 7 Staff Awards: 2007 Chakoumakos elected MSA Fellow Bryan Chakoumakos Neutron scientist Bryan Chakoumakos was recently elected a fellow of the Mineralogical Society of America. A member of the Neutron Scattering Science Division, Bryan leads the Single-Crystal Diffraction Group. The group has five neutron scattering instruments in various stages of design and construction, located at HFIR and SNS. The MSA was founded in 1919 and, among other goals, encourages fundamental research on natural materials and supports education through its publications, educational grants, and courses. Pharos Neutron Detector System Researchers at the Department of Energy's Oak Ridge National Laboratory have won six R&D 100 Awards, given annually by R&D Magazine to the year's

199

Neutron scattering  

Science Journals Connector (OSTI)

... likely to be able to contribute to many different branches of chemistry and secondly because neutron ...neutronscattering ...

A. J. Leadbetter

1977-12-01T23:59:59.000Z

200

Polymer quenched prealloyed metal powder  

DOE Patents (OSTI)

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Hajaligol, Mohammad R. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); German, Randall M. (State College, PA)

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Neutron guide  

DOE Patents (OSTI)

A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Greene, Geoffrey L. (Los Alamos, NM)

1999-01-01T23:59:59.000Z

202

An in situ method for the study of strain broadening using synchrotron X-ray diffraction  

Science Journals Connector (OSTI)

A tensionometer for in situ powder diffraction studies of foils under stress has been constructed and used in a copper foil on beamline 2.3 of the Daresbury SRS. Both peak asymmetry and broadening were observed which was interpreted as being due to a cellular structure with cell walls and cell interiors possessing high and low dislocation densities.

Tang, C.C.

2007-07-13T23:59:59.000Z

203

Superconductivity | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Research Highlights Research Highlights Superconductivity Neutron diffraction reveals semiconducting phase and contributes to new understanding of iron-based superconductors Contact: Huibo Cao New VULCAN tests of Japanese cable for US ITER's central magnet system (2012) Contact: Ke An ARCS maps collaborative magnetic spin behavior in iron telluride (2011) Published Work: "Unconventional Temperature Enhanced Magnetism in Fe1:1Te" Contact: Igor Zaliznyak Doug Scalapino discusses "common thread" linking unconventional superconducting materials (2011) Contact: Douglas Scalapino Materials Engineering Research at SNS Helps International Collaboration on Fusion Energy Scientists and engineers at ORNL are working with the ITER Organization and the Japanese Atomic Energy Agency to resolve issues with a critical

204

Laser Cladding with Multi Elemental Powder Feed  

Science Journals Connector (OSTI)

An investigation is reported on surface cladding with a laser using a mixed powder feed. Success has...

T. Takeda; W. M. Steen; D. R. F. West

1986-01-01T23:59:59.000Z

205

Hydrogen Storage in Diamond Powder Utilizing Plasma NaF Surface Treatment for Fuel Cell Applications  

SciTech Connect

Hydrogen Fuel Cells offer the vital solution to the world's socio-political dependence on oil. Due to existing difficulty in safe and efficient hydrogen storage for fuel cells, storing the hydrogen in hydrocarbon compounds such as artificial diamond is a realistic solution. By treating the surface of the diamond powder with a Sodium Fluoride plasma exposure, the surface of the diamond is cleaned of unwanted molecules. Due to fluorine's electro negativity, the diamond powder is activated and ready for hydrogen absorption. These diamond powder pellets are then placed on a graphite platform that is heated by conduction in a high voltage circuit made of tungsten wire. Then, the injection of hydrogen gas into chamber allows the storage of the Hydrogen on the surface of the diamond powder. By neutron bombardment in the nuclear reactor, or Prompt Gamma Neutron Activation Analysis, the samples are examined for parts per million amounts of hydrogen in the sample. Sodium Fluoride surface treatment allows for higher mass percentage of stored hydrogen in a reliable, resistant structure, such as diamond for fuel cells and permanently alters the diamonds terminal bonds for re-use in the effective storage of hydrogen. The highest stored amount utilizing the NaF plasma surface treatment was 22229 parts per million of hydrogen in the diamond powder which amounts to 2.2229% mass increase.

Leal, David A.; Leal-Quiros, E. [Mechanical Engineering, Polytechnic University of Puerto Rico (Puerto Rico); Velez, Angel; Prelas, Mark A.; Gosh, Tushar [University of Missouri-Columbia, Nuclear Science and Engineering Institute (United States)

2006-12-04T23:59:59.000Z

206

Hydrogen Storage in Diamond Powder Utilizing Plasma NaF Surface Treatment for Fuel Cell Applications  

Science Journals Connector (OSTI)

Hydrogen Fuel Cells offer the vital solution to the worlds socio?political dependence on oil. Due to existing difficulty in safe and efficient hydrogen storage for fuel cells storing the hydrogen in hydrocarbon compounds such as artificial diamond is a realistic solution. By treating the surface of the diamond powder with a Sodium Fluoride plasma exposure the surface of the diamond is cleaned of unwanted molecules. Due to fluorines electro negativity the diamond powder is activated and ready for hydrogen absorption. These diamond powder pellets are then placed on a graphite platform that is heated by conduction in a high voltage circuit made of tungsten wire. Then the injection of hydrogen gas into chamber allows the storage of the Hydrogen on the surface of the diamond powder. By neutron bombardment in the nuclear reactor or Prompt Gamma Neutron Activation Analysis the samples are examined for parts per million amounts of hydrogen in the sample. Sodium Fluoride surface treatment allows for higher mass percentage of stored hydrogen in a reliable resistant structure such as diamond for fuel cells and permanently alters the diamonds terminal bonds for re?use in the effective storage of hydrogen. The highest stored amount utilizing the NaF plasma surface treatment was 22229 parts per million of hydrogen in the diamond powder which amounts to 2.2229% mass increase.

David A. Leal; Angel Velez; Mark A. Prelas; Tushar Gosh; E. Leal?Quiros

2006-01-01T23:59:59.000Z

207

Protein crystallography with spallation neutrons  

SciTech Connect

proteins and oriented molecular complexes. With spallation neutrons and their time dependent wavelength structure, one can select data with an optimal wavelength bandwidth and cover the whole Laue spectrum as time (wavelength) resolved diffraction data. This optimizes data quality with best peak to background ratios and provides spatial and energy resolution to eliminate peak overlaps. Such a Protein Crystallography Station (PCS) has been built and tested at Los Alamos Neutron Science Center. A partially coupled moderator is used to increase flux and data are collected by a Cylindrical He3 detector covering 120' with 200mm height. The PCS is described along with examples of data collected from a number of proteins.

Langan, P. (Paul); Schoenborn, Benno P.

2003-01-01T23:59:59.000Z

208

MESOSCALE SIMULATIONS OF POWDER COMPACTION  

SciTech Connect

Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)

2009-12-28T23:59:59.000Z

209

Neutron skins and neutron stars  

Science Journals Connector (OSTI)

Background: The neutron skin of a heavy nucleus as well as many neutron-star properties are highly sensitive to the poorly constrained density dependence of the symmetry energy.Purpose: To provide for the first time meaningful theoretical errors and to assess the degree of correlation between the neutron-skin thickness of 208Pb and several neutron-star properties.Methods: A proper covariance analysis based on the predictions of an accurately calibrated relativistic functional FSUGold is used to quantify theoretical errors and correlation coefficients.Results: We find correlation coefficients of nearly 1 (or ?1) between the neutron-skin thickness of 208Pb and a host of observables of relevance to the structure, dynamics, and composition of neutron stars.Conclusions: We suggest that a follow-up Lead Radius Experiment (PREX) measurement, ideally with a 0.5% accuracy, could significantly constrain the equation of state of neutron-star matter.

F. J. Fattoyev and J. Piekarewicz

2012-07-05T23:59:59.000Z

210

Neutron Scattering Tutorials | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Scattering Tutorials SHARE Neutron Scattering Tutorials The following lectures were presented at the 2011 and 2010 National School on Neutron & X-Ray Scattering. This...

211

Compaction and Sintering of Mo Powders  

SciTech Connect

To support the development of Mo-99 production by NorthStar Medical Technologies, LLC, Mo metal powders were evaluated for compaction and sintering characteristics as they relate to Mo-100 accelerator target disk fabrication. Powders having a natural isotope distribution and enriched Mo-100 powder were examined. Various powder characteristics are shown to have an effect on both the compaction and sintering behavior. Natural Mo powders could be cold pressed directly to >90% density. All of the powders, including the Mo-100 samples, could be sintered after cold pressing to >90% density. As an example, a compacted Mo-100 disk reached 89.7% density (9.52 g/cm3) after sintering at 1000 C for 1 hr. in flowing Ar/4%H2. Higher sintering temperatures were required for other powder samples. The relationships between processing conditions and the resulting densities of consolidated Mo disks will be presented.

Nunn, Stephen D [ORNL] [ORNL; Kiggans, Jim [ORNL] [ORNL; Bryan, Chris [ORNL] [ORNL

2013-01-01T23:59:59.000Z

212

Neutron detector  

DOE Patents (OSTI)

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Stephan, Andrew C. (Knoxville, TN); Jardret; Vincent D. (Powell, TN)

2011-04-05T23:59:59.000Z

213

High Pressure X-ray Diffraction Study of Potassium Azide  

SciTech Connect

Crystal structure and compressibility of potassium azide was investigated by in-situ synchrotron powder X-ray diffraction in a diamond anvil cell at room temperature up to 37.7 GPa. In the body-centered tetragonal (bct) phase, an anisotropic compressibility was observed with greater compressibility in the direction perpendicular to the plane containing N{sub 3}{sup -} ions than directions within that plane. The bulk modulus of the bct phase was determined to be 18.6(7) GPa. A pressure-induced phase transition may occur at 15.5 GPa.

C Ji; F Zhang; D Hong; H Zhu; J Wu; M Chyu; V Levitas; Y Ma

2011-12-31T23:59:59.000Z

214

Observations of a dynamical-to-kinematic diffraction transition in plastically deformed polycrystalline intermetallic YCu  

SciTech Connect

Unlike most intermetallic compounds, polycrystalline YCu, a B2 (CsCl-type) intermetallic, is ductile at room temperature. The mechanisms for this behavior are not fully understood. In situ neutron diffraction was used to investigate whether a stress-induced phase transformation or twinning contribute to the ductility; however, neither mechanism was found to be active in YCu. Surprisingly, this study revealed that the intensities of the diffraction peaks increased after plastic deformation. It is thought that annealing the samples created nearly perfect crystallinity, and subsequent deformation reduced this high degree of lattice coherency, resulting in a modified mosaic structure that decreased or eliminated the extinction effect. Analysis of changes in diffraction peak intensity showed a region of primary plasticity that exhibits significant changes in diffraction behavior. Fully annealed samples initially contain diffracting volumes large enough to follow the dynamical theory of diffraction. When loaded beyond the yield point, dislocation motion disrupts the lattice perfection, and the diffracting volume is reduced to the point that diffraction follows the kinematic theory of diffraction. Since the sample preparation and deformation mechanisms present in this study are common in numerous material systems, this dynamical to kinematic diffraction transition should also be considered in other diffraction experiments. These measurements also suggest the possibility of a new method of investigating structural characteristics. (C) 2014 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

Williams, Scott H. [Ames Laboratory; Brown, Donald W. [Los Alamos National Laboratory; Clausen, Bjorn [Los Alamos National Laboratory; Russell, Alan [Ames Laboratory; Gschneidner Jr., Karl A. [Ames Laboratory

2014-03-01T23:59:59.000Z

215

Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt  

Science Journals Connector (OSTI)

Multi-component crystals of the anti-inflammatory drug acemetacin were prepared by melt crystallization and their X-ray crystal structures solved using single-crystal and high-resolution powder X-ray diffraction (PXRD) data. The acemetacin-para-aminobenzoic acid adduct and the acemetacin piperazine salt are stable to hydration in the aqueous medium (up to 24 h).

Sanphui, P.

2014-02-28T23:59:59.000Z

216

Neutron activation analysis  

Science Journals Connector (OSTI)

Neutron activation analysis ... Describes the science and techniques of neutron activation analysis. ...

H. R. Lukens

1967-01-01T23:59:59.000Z

217

NEUTRON SCATTERING SHOWS THAT CYTOCHROME b5 PENETRATES DEEPLY INTO THE LIPID BILAYER  

E-Print Network (OSTI)

NEUTRON SCATTERING SHOWS THAT CYTOCHROME b5 PENETRATES DEEPLY INTO THE LIPID BILAYER E. P. GOGOL to lipid vesicles using neutron small-angle scattering methods. To increase scat- tering contrast between of a highly deuterated phospholipid. Small-angle neutron diffraction patterns were collected in a series of H

218

Oxides: neutron and synchrotron X-ray diffraction studies  

Science Journals Connector (OSTI)

......the opal silica-water system. Keywords...oxides, opal silica-water system Received 11...order to perform advanced structure studies...oxides containing water (superionic non-stoichiometric...presence of very heavy atoms and to distin...using the IBR pulsed reactor in structure analysis......

Izabela M. Sosnowska; Makoto Shiojiri

1999-01-01T23:59:59.000Z

219

Cryogenic Neutron Protein Crystallography: routine methods and potential benefits  

SciTech Connect

The use of cryocooling in neutron diffraction has been hampered by several technical challenges such as the need for specialized equipment and techniques. Recently we have developed and deployed equipment and strategies that allow for routine neutron data collection on cryocooled crystals using off the shelf components. This system has several advantages, compared to a closed displex cooling system such as fast cooling coupled with easier crystal mounting and centering. The ability to routinely collect cryogenic neutron data for analysis will significantly broaden the range of scientific questions that can be examined by neutron protein crystallography. Cryogenic neutron data collection for macromolecules has recently become available at the new Biological Diffractometer BIODIFF at FRM II and the Macromolecular Diffractometer (MaNDi) at the Spallation Neutron Source, Oak Ridge National Laboratory. To evaluate the benefits of a cryocooled neutron structure we collected a full neutron data set on the BIODIFF instrument on a Toho-1 lactamase structure at 100K.

Weiss, Kevin L [ORNL; Tomanicek, Stephen J [ORNL; NG, Joseph D [ORNL

2014-01-01T23:59:59.000Z

220

Structural Studies of Al:ZnO Powders and Thin Films | Stanford Synchrotron  

NLE Websites -- All DOE Office Websites (Extended Search)

Structural Studies of Al:ZnO Powders and Thin Films Structural Studies of Al:ZnO Powders and Thin Films Monday, June 18, 2012 - 2:00pm SSRL Main Conference Room 137-322 Dr. Bridget Ingham, Associate Investigator, MacDiarmid Institute for Advanced Materials & Nanotechnology Al-doped ZnO (Al:ZnO) is a promising transparent conducting oxide. We have used complementary synchrotron and laboratory techniques to study the incorporation of Al within the ZnO lattice, and measure its effect on the crystallinity of thin films prepared by sol-gel techniques, with an aim to understand how these properties affect the film conductivity. I will present recent results from Al:ZnO powders and thin films, prepared with varying Al concentrations and calcination temperatures. Solid state 27Al NMR and ex situ X-ray diffraction (XRD) were performed on Al:ZnO

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Neutron Microscope  

Science Journals Connector (OSTI)

We report successful operation of a neutron microscope using ultracold neutrons at the high-flux reactor at Grenoble. A sharp, achromatic image of an object slit was obtained at a magnification of 50. The measured resolution of 0.1 mm was limited mainly by the available beam intensity, not by aberrations.

P. Herrmann; K. -A. Steinhauser; R. Ghler; A. Steyerl; W. Mampe

1985-05-06T23:59:59.000Z

222

Neutron scattering  

Science Journals Connector (OSTI)

... statements that the EMBL outstation in Grenoble "[has an] uncertain future" and that "neutrons have not turned out to be particularly useful for biologists" in Peter Newmark's ... on the European Molecular Biology Laboratory (Nature 338, 724; 1989) require some comment.Neutron ...

S. CUSACK; B. JACROT; R. LEBERMAN; R. MAY; P. TlMMINS; G. ZACCAI

1989-06-01T23:59:59.000Z

223

Process for the synthesis of iron powder  

DOE Patents (OSTI)

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder. 2 figs.

Welbon, W.W.

1983-11-08T23:59:59.000Z

224

Process for the synthesis of iron powder  

DOE Patents (OSTI)

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder.

Not Available

1982-03-06T23:59:59.000Z

225

Modeling of Powder Absorption in Additive Manufacturing  

Science Journals Connector (OSTI)

We have investigated optical absorption by a powder of metal spheres, via ray-trace calculations. The absorptivity significantly exceeds that for normal incidence, because of multiple...

Boley, Charles; Khairallah, Saad; Rubenchik, Alexander M

226

Diffraction dissociation at the LHC  

SciTech Connect

We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

Jenkovszky, Laszlo [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680, Ukraine and Wigner Research Centre for Physics, Hungarian Academy of Sciences 1525 Budapest, POB 49 (Hungary); Orava, Risto [Institute of Physics, Division of Elementary Particle Physics, P.O. Box 64 (Gustaf Haellstroeminkatu 2a), FI-00014 University of Helsinki, Finland and CERN, CH-1211 Geneva 23 (Switzerland); Salii, Andrii [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680 (Ukraine)

2013-04-15T23:59:59.000Z

227

Neutron Polarization  

Science Journals Connector (OSTI)

The production of polarized neutrons in magnetized iron has been studied, using the intense neutron beams available at the Argonne heavy water pile. The theoretical work of Halpern et al., used as a guide in the experiments, has been checked in many respects, with the exception that the polarization cross section p has a measured value of 3.15 barns compared to the theoretical 1 barn. The application of neutron polarization to the measurement of the approach to saturation in ferromagnets is described and preliminary results are reported.

D. J. Hughes; J. R. Wallace; R. H. Holtzman

1948-06-01T23:59:59.000Z

228

Thermal neutron detection system  

DOE Patents (OSTI)

According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

2000-01-01T23:59:59.000Z

229

Densification of nanosized alumina powders by hot isostatic pressing (HIP)  

SciTech Connect

The densification of nanosized alumina powders to compacts of nearly theoretical density by Hot Isostatic Pressing was the aim of this work. Three types of powders produced by the so called exploding wire technique in the mesh size between 20 to 80 nm were used. Because of the big internal friction during dry pressing the densities achieved were only in the range of about 30% TD. Therefore it was necessary to use a second post densification step by cold isostatic pressing (CIP). With pressures as high as 750 MPa the authors received a density of 58% TD. The pellets were sealed in capsules of stainless steel which were densified at different temperatures between 900 C and 1,350 C with pressures between 120 and 300 MPa. The resulting compacts were examined by scanning electron microscopy. The resulting phases were determined by X-ray diffraction. Grain size measurement at the as fabricated compacts was a decisive criterion for the success of the experiments.

Weimar, P.; Knitter, R.; Szabo, D.V. [Forschungszentrum, Karlsruhe (Germany); Krauss, W.

1996-12-31T23:59:59.000Z

230

Neutron Checkup  

Science Journals Connector (OSTI)

Neutron activation analysis is yet another technique in the arsenal of diagnostic methods that physicians can draw on to examine the health of their patients. The University of Washington's school of medicine in Seattle is the first facility in the ...

1969-11-10T23:59:59.000Z

231

Neutron Reflectometry  

Science Journals Connector (OSTI)

Neutron reflectometry is a relatively new technique [1,2]. In the last years, it has been extensively used for solving soft matter problems like polymer mixing [3,4] or the structure of liquids at the surface [5,

Claude Fermon; Frdric Ott; Alain Menelle

1999-01-01T23:59:59.000Z

232

Neutron Tomography and Space  

E-Print Network (OSTI)

Kevin Shields, Optimization of neutron tomography for rapidNEUTRON TOMOGRAPHY AND SPACE Hal Egbert, Ronald Walker, R.industrial applications[1]. Neutron Computed Tomography was

Egbert, Hal; Walker, Ronald; Flocchini, R.

2007-01-01T23:59:59.000Z

233

Neutron range spectrometer  

DOE Patents (OSTI)

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

Manglos, S.H.

1988-03-10T23:59:59.000Z

234

Neutron scattering techniques as a tool for nondestructive testing  

Science Journals Connector (OSTI)

Neutron scattering techniques such as neutron diffraction, Small-Angle Neutron Scattering (SANS) and Neutron Reflectivity (NREF) are very powerful tools for the nondestructive study of materials. The corresponding experimental facilities at a Greek research reactor and demonstrative experiments of their employment in the nondestructive testing of materials are presented. Neutron diffraction was applied in the study of irradiation effects on SiCf /SiC composites in view of their application to future fusion reactors. SiC materials are important in the aerospace industry and their oxidation at high temperatures was investigated by NREF. Finally, a SANS study of the precipitation of the aerospace Al-8.9at%Li alloy is presented.

G. Apostolopoulos; K. Mergia; A.G. Youtsos

2009-01-01T23:59:59.000Z

235

Detonation Diffraction into a Confined Volume.  

E-Print Network (OSTI)

??Detonation diffraction has been, and remains, an active area of research. However, detonation diffraction into a confined volume, and specifically the transformation of a planar (more)

Polley, Nolan Lee

2012-01-01T23:59:59.000Z

236

Neutron scattering investigation of the magnetic order in single crystalline BaFe2As2  

SciTech Connect

The magnetic structure of BaFe{sub 2}As{sub 2} was determined from polycrystalline neutron diffraction measurements soon after the ThCr{sub 2}Si{sub 2}-type FeAs-based superconductors were discovered. Both the moment direction and the in-plane antiferromagnetic wavevector are along the longer a-axis of the orthorhombic unit cell. There is only one combined magnetostructural transition at {approx}140 K. However, a later single-crystal neutron diffraction work reported contradicting results. Here, we show neutron diffraction results from a single-crystal sample, grown by a self-flux method, that support the original polycrystalline work.

Bao, Wei [Los Alamos National Laboratory; Qiu, Y [NIST; Kofu, M [UNIV OF VA; Lee, S - H [UNIV OF VA; Chang, S [NIST; Wu, T [HEFEI NAT. LAB.; Wu, G [HEFEI NAT. LAB; Chen, X H [HEFEI NAT. LAB

2008-01-01T23:59:59.000Z

237

On the microstructure of nanoporous gold: an x-ray diffraction study  

SciTech Connect

The evolution of the grain structure, internal stresses, and the lattice misorientations of nanoporous gold (npAu) during dealloying of bulk (3D) Ag-Au alloy samples was studied by various in-situ and ex-situ X-ray diffraction techniques including powder and Laue diffraction. The experiments reveal that the dealloying process preserves the original crystallographic structure, but leads to a small spread in orientations within individual grains. Furthermore, most grains develop in-plane tensile stress. The feature size of the developing nanoporous structure increases with increasing dealloying time.

Van Petegem, S; Brandstetter, S; Maa?, R; Schmitt, B; Borca, C; Van Swygenhoven, H; Hodge, A M; El-Dasher, B S; Biener, J

2008-08-26T23:59:59.000Z

238

Magnetic neutron scattering (invited)  

Science Journals Connector (OSTI)

The application of neutron scattering techniques to magnetic problems is reviewed. We will first discuss diffraction techniques used to solve magnetic structures as well as to measure magnetic form factors order parameters critical phenomena and the scattering from low?dimensional systems. We will also discuss inelastic scattering techniques including polarized beam methods utilized to determine the spin dynamics of various materials. Information will be provided about the types of spectrometers available at the user?oriented national facilities located at Argonne National Laboratory Brookhaven National Laboratory Los Alamos National Laboratory The National Institute of Standards and Technology and Oak Ridge National Laboratory as well as the spectrometers at the Missouri University Research Reactor.

J. W. Lynn

1994-01-01T23:59:59.000Z

239

Boron-copper neutron absorbing material and method of preparation  

DOE Patents (OSTI)

A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry (Palos Hts., IL)

1991-01-01T23:59:59.000Z

240

Electrochemical Studies of Packed Iron Powder Electrodes: Effects...  

NLE Websites -- All DOE Office Websites (Extended Search)

of Packed Iron Powder Electrodes: Effects of Common Constituents of Natural Waters on Corrosion Electrochemical Studies of Packed Iron Powder Electrodes: Effects of Common...

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Models to analyze small-angle neutron scattering from unilamellar lipid vesicles Norbert Kucerka* and John F. Nagle  

E-Print Network (OSTI)

Models to analyze small-angle neutron scattering from unilamellar lipid vesicles Norbert Kucerka from small-angle neutron scattering of unilamellar vesicles. DOI: 10.1103/PhysRevE.69.051903 PACS discrete diffraction peaks that occur for multilamellar arrays, the scattering of x rays or neutrons from

Nagle, John F.

242

Neutron Repulsion  

E-Print Network (OSTI)

Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding how: a.) The Sun generates and releases neutrinos, energy and solar-wind hydrogen and helium; b.) An inhabitable planet formed and life evolved around an ordinary-looking star; c.) Continuous climate change - induced by cyclic changes in gravitational interactions of the Sun's energetic core with planets - has favored survival by adaptation.

Oliver K. Manuel

2011-02-08T23:59:59.000Z

243

Fast-Neutron Handbook  

Science Journals Connector (OSTI)

... FAST neutron physics, in the present context, concerns the study of interactions of atomic nuclei with neutrons ...

J. H. MONTAGUE

1961-06-10T23:59:59.000Z

244

Neutron Scattering User Program | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

User Program SHARE Neutron Scattering Can Benefit Your Research Neutron scattering has applications in almost every technical and scientific field, from biology and chemistry to...

245

A QCD analysis of ZEUS diffractive data  

E-Print Network (OSTI)

ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to costrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data.

ZEUS Collaboration

2009-11-23T23:59:59.000Z

246

Diffraction encoded position measuring apparatus  

DOE Patents (OSTI)

When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection.

Tansey, Richard J. (Thousand Oaks, CA)

1991-01-01T23:59:59.000Z

247

Diffraction encoded position measuring apparatus  

DOE Patents (OSTI)

When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection. 3 figures.

Tansey, R.J.

1991-09-24T23:59:59.000Z

248

Neutron Polarization  

Science Journals Connector (OSTI)

Experiments for the determination of the polarization cross section p of iron with monochromatic and non-monochromatic neutrons are described. The absolute value of p as well as its dependence on the neutron velocity is found to be in good agreement with the recent calculations of Steinberger and Wick and also with other experiments. For a complex neutron spectrum originating from a paraffin moderator p is found to be (2.350.1)10-24 cm2 in agreement with previous investigations. It is shown that the larger value of 3.1510-24 cm2 found by Hughes, Wallace, and Holtzman must be due to spectral differences. The approach of the magnetization of iron towards saturation is also investigated.

J. Fleeman; D. B. Nicodemus; H. H. Staub

1949-12-15T23:59:59.000Z

249

Powder Dropper | Princeton Plasma Physics Lab  

NLE Websites -- All DOE Office Websites (Extended Search)

Powder Dropper This device releases micron-sized dust particles at a controlled rate through an aperture in a vibrating crystal. The amount of dust released ranges from a few...

250

Continuous blending of dry pharmaceutical powders  

E-Print Network (OSTI)

Conventional batch blending of pharmaceutical powders coupled with long quality analysis times increases the production cycle time leading to strained cash flows. Also, scale-up issues faced in process development causes ...

Pernenkil, Lakshman

2008-01-01T23:59:59.000Z

251

Synthesis and processing of monosized oxide powders  

DOE Patents (OSTI)

Uniform-size, high-purity, spherical oxide powders are formed by hydrolysis of alkoxide precursors in dilute alcoholic solutions. Under controlled conditions (concentrations of 0.03 to 0.2 M alkoxide and 0.2 to 1.5 M water, for example) oxide particles on the order of about 0.05 to 0.7 micron can be produced. Methods of doping such powders and forming sinterable compacts are also disclosed.

Barringer, Eric A. (Waltham, MA); Fegley, Jr., M. Bruce (Waban, MA); Bowen, H. Kent (Belmont, MA)

1985-01-01T23:59:59.000Z

252

Effect of reductant and PVP on morphology and magnetic property of ultrafine Ni powders prepared via hydrothermal route  

SciTech Connect

Graphical abstract: The ultrafine Ni powders with the shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using different reductants. Their saturation magnetization, remanent magnetization and coercivity sequentially increase, and the coercivity of hexagonal sheet-like Ni powders increases by 25% compared with the Ni bulk counterpart. - Highlights: The ultrafine Ni powders with various shapes of sphere, fish-bone, hexagonal sheet, etc. Facile and one-step hydrothermal reduction using three reductants and PVP additive was developed. Magnetic properties of the ultrafine Ni powders with different shapes were measured. Compared with bulk Ni material, coercivity of hexagonal sheet Ni increases by 25%. The formation mechanism of the shapes was suggested. - Abstract: The ultrafine nickel particles with different shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using hydrazine hydrate, sodium hypophosphite and ethylene glycol as reductants, polyvinylpyrrolidone as structure-directing agent. It has been verified with the characterization of X-ray powder diffraction and transmission/scanning electronic microscopy that as-prepared products belong to face-centered cubic structure of nickel microcrystals with high purity and fine dispersity. The magnetic hysteresis loops measured at room temperature reveal that the values of saturation magnetization, remanent magnetization and coercivity rise sequentially from silknet, sphere to hexagonal sheet. In comparison with nickel bulk counterpart, the coercivity of the hexagonal sheet nickel powders increases by 25%.

Zhang, Jun, E-mail: j-zhang@126.com; Wang, Xiucai; Li, Lili; Li, Chengxuan; Peng, Shuge

2013-10-15T23:59:59.000Z

253

Tantalum powder consolidation, modeling and properties  

SciTech Connect

A systematic approach was taken to investigate the consolidation of tantalum powders. The effects of sinter time, temperature and ramp rate; hot isostatic pressing (HIP) temperature and time; and powder oxygen content on consolidation density, kinetics, microstructure, crystallographic texture, and mechanical properties have been evaluated. In general, higher temperatures and longer hold times resulted in higher density compacts with larger grain sizes for both sintering and HIP`ing. HIP`ed compacts were consistently higher in density than sintered products. The higher oxygen content powders resulted in finer grained, higher density HIP`ed products than the low oxygen powders. Texture analysis showed that the isostatically processed powder products demonstrated a near random texture. This resulted in isotropic properties in the final product. Mechanical testing results showed that the HIP`ed powder products had consistently higher flow stresses than conventionally produced plates, and the sintered compacts were comparable to the plate material. A micromechanics model (Ashby HIP model) has been employed to predict the mechanisms active in the consolidation processes of cold isostatic pressing (CIP), HIP and sintering. This model also predicts the density of the end product and whether grain growth should be expected under the applied processing conditions.

Bingert, S.R.; Vargas, V.D.; Sheinberg, H.C.

1996-10-01T23:59:59.000Z

254

Neutron scattering from myelin revisited: bilayer asymmetry and water-exchange kinetics  

Science Journals Connector (OSTI)

The structure of internodal myelin in the rodent central and peripheral nervous systems has been determined using neutron diffraction. The kinetics of water exchange in these tissues is also described.

Denninger, A.R.

2014-11-22T23:59:59.000Z

255

Hydrogen bonds of DsrD protein revealed by neutron crystallography  

Science Journals Connector (OSTI)

Hydrogen bonds of DNA-binding protein DsrD have been determined by neutron diffraction. In terms of proton donors and acceptors, DsrD protein shows striking differences from other proteins.

Chatake, T.

2008-04-18T23:59:59.000Z

256

The Neutron  

Science Journals Connector (OSTI)

The writers point out that the postulation of the existence of the "neutron," a combination of an electron and a proton, of small size and low energy would be very useful in explaining a number of atomic and cosmic phenomena. They find that a mathematical treatment based on existing theory leads to indications of such a state but no definite proof.

R. M. Langer and N. Rosen

1931-06-15T23:59:59.000Z

257

SNS Instrument System Beam Lines | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

SNS Instrument Beam Lines SNS Instrument Beam Lines This diagram shows the beam lines designated for currently funded instruments. Clicking on an instrument description will take you to the page for that instrument. Clicking anywhere else on the image will open a full-size, printable PDF file. SNS Instrument Layout Backscattering Spectrometer (BASIS) Disordered Materials Diffractometer (NOMAD) Wide Angular-Range Chopper Spectrometer (ARCS) Fine-Resolution Fermi Chopper Spectrometer (SEQUOIA) Coming Soon - Vibrational Spectrometer (VISION) Neutron Spin Echo (NSE) Hybrid Spectrometer (HYSPEC) Fundamental Neutron Physics Beamline (FNPB) Single Crystal Diffractometer (TOPAZ) Versatile Neutron Imaging Instrument (VENUS) Macromolecular Diffractometer (MaNDi) Powder Diffractometer (POWGEN3) Engineering Diffractometer (VULCAN) Extended Q-Range Small Angle Neutron Diffractometer (EQ-SANS) Cold Neutron Chopper Spectrometer (CNCS) Liquids (horizontal surface) Reflectometer (LR) Magnetic Advanced Grazing InCidence Spectrometer (MAGICS) High Pressure Diffractometer (SNAP) Coming Soon - Elastic Diffuse Scattering Spectrometer (CORELLI)

258

NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS  

E-Print Network (OSTI)

NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS AND POLARIZED 3He R. GOLUB~and Steve K REPORTS (Review Section of Physics Letters) 237, No. 1(1994)1--62. PHYSICS REPORTS North-Holland Neutron electric-dipole moment, ultracold neutrons and polarized 3He R. Goluba and Steve K. Lamoreauxb a

259

Structural and spectroscopic analyses of europium doped yttrium oxyfluoride powders prepared by combustion synthesis  

SciTech Connect

A facile widely spread technique employed to produce low-cost high-yield oxide powders, combustion synthesis, was used to prepare yttrium oxyfluoride crystalline ceramic powders. The structure of the powders was analyzed by X-ray powder diffraction and Rietveld refinement. Samples heat treated at 700 C had a predominance of vernier orthorhombic Y{sub 6}O{sub 5}F{sub 8} phase, while samples heat treated at 800 C crystallized in stoichiometric rhombohedral YOF phase. The samples were doped with luminescent europium trivalent ions (Eu{sup 3+}) in different concentrations (115 wt.%) and Judd-Ofelt theory was used to probe the distortion from the inversion symmetry of the local crystal field and the degree of covalency between the rare-earth ion and the surrounding ligands. The luminescence lifetime was measured and the luminescence quantum efficiency (LQE) was estimated. We observed that Eu{sup 3+}:Y{sub 6}O{sub 5}F{sub 8} samples presented higher LQE in spite of the larger local crystal field anisotropy found for Eu{sup 3+}:YOF samples.

Rakov, Nikifor [PG-Cincia dos Materiais, Universidade Federal do Vale do So Francisco, 48902-300 Juazeiro, BA (Brazil)] [PG-Cincia dos Materiais, Universidade Federal do Vale do So Francisco, 48902-300 Juazeiro, BA (Brazil); Guimares, R. B.; Maciel, Glauco S. [Instituto de Fsica, Universidade Federal Fluminense, 24210-346 Niteri, RJ (Brazil)] [Instituto de Fsica, Universidade Federal Fluminense, 24210-346 Niteri, RJ (Brazil); Lozano B, W. [Departamento de Fsica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)] [Departamento de Fsica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2013-07-28T23:59:59.000Z

260

Slow Neutron Scattering by the Titanium Isotopes  

Science Journals Connector (OSTI)

Neutron diffraction studies are reported on isotopically enriched samples of TiO2 from which are evaluated the coherent scattering amplitudes of the titanium isotopes. Scattering amplitudes of +0.48, +0.33, -0.58, +0.08, and +0.5510-12 cm were established for the titanium isotopes of mass 46, 47, 48, 49, and 50, respectively. The major isotope Ti48 is thus responsible for the anomalous scattering amplitude, -0.3410-12 cm, characteristic of the normal element. Pronounced nuclear scattering resonance effects on the observed neutron scattering are suggested to occur for most of the isotopes.

C. G. Shull; M. K. Wilkinson; M. H. Mueller

1960-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Neutron scattering studies of carbon nanotubes  

Science Journals Connector (OSTI)

We report on neutron scattering studies of single wall carbon nanotubes (SWNT). Small angle scattering was used to investigate the structure of SWNT suspensions. Diffraction data were compared to calculations on finite-size bundles of SWNT in order to estimate the distribution of tube diameters. Lastly we present an inelastic neutron scattering study of the density of phonon states in SWNT. In the frequency range of intramolecular modes the measured spectrum is found to be in good agreement with that calculated on an isolated (10 10) nanotube.

E. Anglaret; S. Rols; J. L. Sauvajol

1999-01-01T23:59:59.000Z

262

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

Wood, J.L.

1992-12-01T23:59:59.000Z

263

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

264

Preparation and X-Ray diffraction studies of curium hydrides  

SciTech Connect

Curium hydrides were prepared by reaction of curium-248 metal with hydrogen and characterized by X-ray powder diffraction. Several of the syntheses resulted in a hexagonal compound with average lattice parameters of a/sub 0/ = 0.3769(8) nm and c/sub 0/ = 0.6732(12) nm. These products are considere to be CmH/sub 3//sup -//sub 8/ by analogy with the behavior of lanthanide-hydrogen and lighter actinide-hydrogen systems. Face-centered cubic products with an average lattice parameter of a/sub 0/ = 0.5322(4) nm were obtained from other curium hydride preparations. This parameter is slightly smaller than that reported previously for cubic curium dihydride, CmH /SUB 2-x/ (B.M. Bansal and D. Damien. Inorg. Nucl. Chem. Lett. 6 603, 1970). The present results established a continuation of typical heavy trivalent lanthanidelike behavior of the transuranium actinide-hydrogen systems through curium.

Gibson, J.K.; Maire, R.G.

1985-10-01T23:59:59.000Z

265

Neutron Diffraction Performance Based on Multiple Reflection Monochromator for High-Resolution Neutron Radiography  

Science Journals Connector (OSTI)

The effects of multiple Bragg reflections in single crystal can be observed when more than one set of planes are simultaneously operative for a given wavelength i.e. when more than two reciprocal lattice point...

Pavel Mikula; Miroslav Vrana

2007-01-01T23:59:59.000Z

266

Fabrication of ultrafine tungsten-based alloy powders by novel soda reduction process  

SciTech Connect

A novel reduction method has been developed to fabricate ultrafine tungsten heavy alloy powders, with ammonium metatungstate (AMT), iron(II) chloride tetrahydrate (FeCl{sub 2}.4H{sub 2}O), nickel(II) chloride hexahydrate (NiCl{sub 2}.6H{sub 2}O) as source materials and sodium tungstate dihydrate (Na{sub 2}WO{sub 4}.2H{sub 2}O) as a reductant. In the preparation of mixtures the amounts of the source components were chosen so as to obtain alloy of 93W-5Ni-2Fe composition (wt.%). The obtained powders were characterized by X-ray diffraction, XPS, field-emission scanning microscope (FESEM), and chemical composition was analyzed by EDX.

Lee, Dong-Won [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of)] [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of); Turaev, Farkhod, E-mail: farkhod_2002@yahoo.com [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of)] [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of); Kim, Ju-Hyeong [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of)] [Powder Technology Research Group, Korea Institute of Materials Science (KIMS), Changwon, Kyungnam, 641-010 (Korea, Republic of); Yang, Mingchuan [W-base Heavy Alloy Research Group, Institute of Metal Research (IMR), 72 Wenhua-road, Shenyang, 110016 (China)] [W-base Heavy Alloy Research Group, Institute of Metal Research (IMR), 72 Wenhua-road, Shenyang, 110016 (China)

2010-03-15T23:59:59.000Z

267

Innovative Powder Processing of Oxide Dispersion Strengthened ODS Ferritic Stainless Steels  

SciTech Connect

An innovative gas atomization reaction synthesis technique was employed as a viable method to dramatically lower the processing cost for precursor oxide dispersion forming ferritic stainless steel powders (i.e., Fe-Cr-(Hf,Ti)-Y). During this rapid solidification process the atomized powders were enveloped by a nano-metric Cr-enriched metastable oxide film. Elevated temperature heat treatment was used to dissociate this metastable oxide phase through oxygen exchange reactions with Y-(Hf,Ti) enriched intermetallic compound precipitates. These solid state reactions resulted in the formation of highly stable nano-metric mixed oxide dispersoids (i.e., Y-Ti-O or Y-Hf-O) throughout the alloy microstructure. Subsequent high temperature (1200 C) heat treatments were used to elucidate the thermal stability of each nano-metric oxide dispersoid phase. Transmission electron microscopy coupled with X-ray diffraction was used to evaluate phase evolution within the alloy microstructure.

Rieken, Joel; Anderson, Iver; Kramer, Matthew

2011-04-01T23:59:59.000Z

268

Synthesis and Characterization of Lithium Ferrite LiFe 5 O 8 Powder by Sol Gel Method  

Science Journals Connector (OSTI)

Lithium ferrite LiFe 5 O 8 powder has been prepared by sol gel method. Lithium acetate and iron nitrate are mixed together in the ethanol solution. The mixture is then slow heated to obtain the precursor. The precursor materials are sent for characterization using Thermal Gravimetric Analyzer (TGA) X?Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Then the high energy ball milling method was applied to obtain the nano sized lithium ferrite.

N. S. A. Puad; A. F. M. Fadzil; R. Yusof; N. Kamarulzaman

2010-01-01T23:59:59.000Z

269

Colossal Light-Induced Refractive-Index Modulation for Neutrons in Holographic Polymer-Dispersed Liquid Crystals  

SciTech Connect

We report strong diffraction of cold neutrons from an only 30 {mu}m thick holographic polymer-dispersed liquid crystal (H-PDLC) transmission grating. The light-induced refractive-index modulation for neutrons is about 10{sup -6}, i.e., nearly 2 orders of magnitude larger than in the best photo-neutron-refractive materials probed up to now. This makes H-PDLCs a promising candidate for fabricating neutron-optical devices.

Fally, Martin; Ellabban, Mostafa A. [Nonlinear Physics Group, Faculty of Physics, Universitaet Wien, Boltzmanngasse 5, A-1090 Vienna (Austria); Drevensek-Olenik, Irena [Nonlinear Physics Group, Faculty of Physics, Universitaet Wien, Boltzmanngasse 5, A-1090 Vienna (Austria); Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, and J. Stefan Institute, Jamova 39, SI 1001 Ljubljana (Slovenia); Pranzas, Klaus P.; Vollbrandt, Juergen [GKSS Forschungszentrum, D-21502 Geesthacht (Germany)

2006-10-20T23:59:59.000Z

270

Neutron Scattering Facilities 1982  

NLE Websites -- All DOE Office Websites (Extended Search)

NEUTRON SOURCES NEUTRON SOURCES Types of Sources U.S. Sources Available for Users Plans for the Future The Neutron Scattering Society of America (NSSA) SNS/ANL School on Neutron and x-Ray Scattering, June 2011 Jim Rhyne Lujan Neutron Scattering Center Los Alamos National Lab. What do we need to do neutron scattering? * Neutron Source - produces neutrons * Diffractometer or Spectrometer - Allows neutrons to interact with sample - Sorts out discrete wavelengths by monochromator (reactor) or by time of flight (pulse source) - Detectors pick up neutrons scattered from sample * Analysis methods to determine material properties * Brain power to interpret results Sources of neutrons for scattering * Nuclear Reactor - Neutrons produced from fission of 235 U - Fission spectrum neutrons

271

Interaction between laser beam and powder stream in the process of laser cladding with powder feeding  

Science Journals Connector (OSTI)

Based on LambertBeer theorem and Mie's theory, the attenuation of laser power by a powder stream was calculated and the laser intensity distribution at the laser spot on the surface of a workpiece was obtained. Simultaneously, the temperature distribution of the powder particles arriving at different sites on the surface of the workpiece was computed following the heat equilibrium principle. The computed results revealed that for a given stream spread and speed of powder particles, the intensity distribution of the laser spot and the temperature distribution of the powder particles reaching the surface of the workpiece are both greatly affected by the powder feeding rate and the feeding angle. It is suggested that the presented results should be considered in the laser cladding process in order to control the dynamic processes in a laser molten pool.

Yan-Lu Huang; Gong-Ying Liang; Jun-Yi Su; Jian-Guo Li

2005-01-01T23:59:59.000Z

272

Die-target for dynamic powder consolidation  

DOE Patents (OSTI)

A die/target is disclosed for consolidation of a powder, especially an atomized rapidly solidified metal powder, to produce monoliths by the dynamic action of a shock wave, especially a shock wave produced by the detonation of an explosive charge. The die/target comprises a rectangular metal block having a square primary surface with four rectangular mold cavities formed therein to receive the powder. The cavities are located away from the geometrical center of the primary surface and are distributed around such center while also being located away from the geometrical diagonals of the primary surface to reduce the action of reflected waves so as to avoid tensile cracking of the monoliths. The primary surface is covered by a powder retention plate which is engaged by a flyer plate to transmit the shock wave to the primary surface and the powder. Spawl plates are adhesively mounted on other surfaces of the block to act as momentum traps so as to reduce reflected waves in the block.

Flinn, John E. (Idaho Falls, ID); Korth, Gary E. (Blackfoot, ID)

1986-01-01T23:59:59.000Z

273

Neutron Polarization  

Science Journals Connector (OSTI)

The neutron polarization cross section of iron has been measured as a function of energy from 0.7 to 3.3A by two methods: using the single transmission effect in a block of polycrystalline iron at energies selected by a quartz crystal monochromator; and using a single crystal of magnetized magnetite to analyze the beam emerging from the iron polarizer, the magnetite crystal itself serving as monochromator. The measured values are compared with those of other observers and the theoretically expected values. These are found to agree fairly well within the limits of accuracy of the measurements and existing knowledge of the wave function of the iron 3d shell. The two techniques were used also to determine the average polarization (32 percent) as seen by a 1v detector in a beam of reactor neutrons emerging from a 4-cm thick polarizing block of iron. Problems and techniques associated with the measurement of the average polarization of a continuous spectrum are discussed. A simplified experimental treatment of the problem of beam "hardening" is described. A description is given of the use of the magnetic resonance method in conjunction with a single-crystal magnetite analyzer for the measurement of neutron polarization.

C. P. Stanford; T. E. Stephenson; L. W. Cochran; S. Bernstein

1954-04-15T23:59:59.000Z

274

Neutron Gas  

Science Journals Connector (OSTI)

We assume that the neutron-neutron potential is well-behaved and velocity-dependent. We can then apply perturbation theory to find the energy per particle of a neutron gas, in the range of Fermi wave numbers 0.5

J. S. Levinger and L. M. Simmons

1961-11-01T23:59:59.000Z

275

Detonation Diffraction into a Confined Volume  

E-Print Network (OSTI)

Detonation diffraction has been, and remains, an active area of research. However, detonation diffraction into a confined volume, and specifically the transformation of a planar detonation into a cylindrical detonation, is an area which has received...

Polley, Nolan Lee

2012-02-14T23:59:59.000Z

276

A Model Graphene Diffraction Pattern Frank Rioux  

E-Print Network (OSTI)

A Model Graphene Diffraction Pattern Frank Rioux The purpose of this tutorial is to model graphene d Pj k px j py k 2 i 1 A Graphene Model Diffraction Pattern #12;

Rioux, Frank

277

Diffractive dijet and W production in CDF  

SciTech Connect

Results on diffractive dijet and W-boson production from CDF are reviewed and compared with predictions based on factorization of the diffractive structure function of the proton measured in deep inelastic scattering at HERA.

Goulianos, K. [Rockefeller Univ., New York, NY (United States)

1998-06-01T23:59:59.000Z

278

Effect of the concentration of inhomogeneities on the multiple small-angle neutron scattering  

SciTech Connect

The interference effects manifested during multiple small-angle neutron scattering (MSANS) on a chaotically arranged close-packed ensemble of scatterers have been studied. MSANS measurements have been performed for mixtures of Al and Ti-Zr alloy powders. It is shown that the results can be satisfactorily described based on a theory that takes into account spatial correlations in the arrangement of powder grains.

Abov, Yu. G.; Dzheparov, F. S.; Elyutin, N. O.; Lvov, D. V., E-mail: lvov@itep.ru; Tyulyusov, A. N. [Institute for Theoretical and Experimental Physics (Russian Federation)] [Institute for Theoretical and Experimental Physics (Russian Federation)

2013-03-15T23:59:59.000Z

279

Scalar Diffraction in Terms of Coherence  

Science Journals Connector (OSTI)

...research-article Scalar Diffraction in Terms of Coherence W. H. Steel In scalar diffraction theory...correlation function, here called the 'coherence', rather than in quantities such as...diffraction is developed here based on the coherence between radiation at pairs of points...

1959-01-01T23:59:59.000Z

280

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figs.

Salyer, I.O.

1995-12-26T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figures.

Salyer, I.O.

1994-12-06T23:59:59.000Z

282

Publications | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Publications SHARE Publications The Neutron Science publications system contains peer-reviewed publications based on research conducted at ORNL's Neutron Science facilities or...

283

Neutron Scattering Facilities  

Science Journals Connector (OSTI)

The past history, present performance and future prospects for neutron scattering facilities will be discussed. Special features of neutron scattering techniques applicable to biological problems will be ... . Th...

D. L. Price

1996-01-01T23:59:59.000Z

284

Current Status and Future Works of Neutron Scattering Laboratory at BATAN in Serpong  

SciTech Connect

Current status of neutron beam instruments using neutrons produced by the Multi Purpose Research Reactor--30MWth (MPR 30, RSG GA Siwabessy) located in Serpong is presented. Description of the reactor as the neutron source is mentioned briefly. There are six neutron beam tubes coming from the beryllium reflector surrounding half of the reactor core providing neutrons in the experimental hall of the reactor (XHR). Four of them are dedicated to R and D in materials science using neutron scattering techniques. Neutron Radiography Facility (NRF), Triple Axis Spectrometer (TAS) and Residual Stress Measurement (RSM) Diffractometer are installed respectively at beam tubes S2, S4 and S6. The largest neutron beam tube (S5) is exploited to accommodate two neutron guide tubes that transfer the neutrons to a neighbouring building called neutron guide hall (NGH). There are three other neutron beam instruments installed in this building, namely Small Angle Neutron Scattering (SANS) Spectrometer (SMARTer), High Resolution SANS (HRSANS) Spectrometer and High Resolution Powder Diffractometer (HRPD). In the XHR, a Four Circle and Texture Diffractometer (FCD/TD) is attached to one of the neutron guide tubes. These seven instruments were installed to utilize the neutrons for materials science research, and recently the RSM diffractometer has shown its capabilities in identifying different amount of stress left due to different treatments of welding in fuel cladding, while the SANS spectrometer is now gaining capabilities in identifying different sizes and shapes of macromolecules in polymers as well as investigations of magnetic samples. In the mean time, non-destructive tests using the NRF is gathering more confidence from some latest real time measurements eventhough there are still some shortcomings in the components and their alignments. Future works including improvement of each facility and its components, even replacement of some parts are necessary and have to be carried out carefully. A plan for developing a neutron reflectometer at one of the neutron guide in the Neutron Guide Hall is also part of the near future activities.

Ikram, A. [Center of Technology for Nuclear Industrial Materials, National Nuclear Energy Agency of Indonesia (BATAN) Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia)

2008-03-17T23:59:59.000Z

285

Calculations of neutron spectra after neutronneutron scattering  

Science Journals Connector (OSTI)

A direct neutronneutron scattering length, ann, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of ann will not only help resolve conflicting results of ann by indirect means, but also in comparison to the protonproton scattering length, app, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrumMaxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermalthermal and thermalepithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

B E Crawford; S L Stephenson; C R Howell; G E Mitchell; W Tornow; W I Furman; E V Lychagin; A Yu Muzichka; G V Nekhaev; A V Strelkov; E I Sharapov; V N Shvetsov

2004-01-01T23:59:59.000Z

286

Dr. Michael Agamalian | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Dr. Michael Agamalian Dr. Michael Agamalian Lead Scientist, Ultra-Small-Angle Neutron Scattering (USANS), SNS Education PhD in Physics, St. Petersburg Nuclear Physics Institute, Russia Description of Research Michael Agamalian and collaborators have made important contributions to the development of the ORNL Bonse-Hart Ultra-Small-Angle Neutron Scattering instrument (USANS). In particular, they adopted the classical X-ray Bonse-Hart technique for neutrons by modifying the Si channel-cut crystal and introducing an additional element, a Cd absorber. This innovation, combined with application of a specialized chemical-mechanical treatment of the diffractive surfaces of the Si channel-cut crystal, has increased the sensitivity of the ORNL USANS instrument by three orders of magnitude. This

287

Chemical and Engineering Materials | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Chemical and Engineering Materials Chemical and Engineering Materials SHARE Chemical and Engineering Materials Neutron-based research at SNS and HFIR in Chemical and Engineering Materials strives to understand the structure and dynamics of chemical systems and novel engineering materials. The user community takes advantage of capabilities of neutron scattering for measurements over wide ranges of experimental and operating conditions, including studies of chemical and physical changes in situ. User experiments with diffraction, small-angle scattering, inelastic and quasi-elastic scattering, and neutron imaging instruments address a range of problems in chemistry and in engineering materials research. Current areas of research supported within Chemical and Engineering Materials include: The structure and dynamics of electrical energy storage materials

288

Spallation Neutron Source | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Spallation Neutron Source SNS site, Spring 2012 The 80-acre SNS site is located on the east end of the ORNL campus and is about a three-minute drive from her sister neutron...

289

Neutron lifetime measured with stored ultracold neutrons  

Science Journals Connector (OSTI)

The neutron lifetime has been measured by counting the neutrons remaining in a fluid-walled bottle as a function of the duration of storage. Losses of neutrons caused by the wall reflections are eliminated by varying the bottle volume-to-surface ratio. The result obtained is ??=887.63 s.

W. Mampe; P. Ageron; C. Bates; J. M. Pendlebury; A. Steyerl

1989-08-07T23:59:59.000Z

290

Neutron-Neutron Quasifree Scattering  

Science Journals Connector (OSTI)

The reaction D(n ,2n)p has been measured at Einc=14.1 MeV, ?n (3)=?n(4)=30?, ?=180?, and the results are compared with the predictions of two separable-potential models. Neutron-proton and proton-proton quasifree scattering from nucleon + deuteron reactions at 14 MeV are also compared with the predictions of the same models. The upper limit of 2 mb/sr2 is determined for the reaction D(n,n?)d.

Ivo Slaus; J. W. Sunier; G. Thompson; J. C. Young; J. W. Verba; D. J. Margaziotis; P. Doherty; R. T. Cahill

1971-03-29T23:59:59.000Z

291

Robust powder auto-indexing using many peaks  

Science Journals Connector (OSTI)

A new algorithm, CONOGRAPH, carries out exhaustive powder auto-indexing in a short time, even if the q values of many peaks are used for robust powder auto-indexing. Some results from CONOGRAPH are presented.

Oishi-Tomiyasu, R.

2014-03-11T23:59:59.000Z

292

Development and Testing of a BI-2212 Textured Powder Conductor  

E-Print Network (OSTI)

for Praxair powder in a 500 cP epoxy. .................................................................................................................. 23 Fig. 8: Texture vs. time for various epoxy and powder combinations. All data from an 8.9 T applied...

Damborsky, Kyle

2014-03-10T23:59:59.000Z

293

How Magnetic Dimers Interact to Create Long-Range Order  

NLE Websites -- All DOE Office Websites (Extended Search)

distortions. The x-ray data also enabled the researchers to pinpoint the phase transition temperature as being 122 K. Complementary high-resolution powder neutron diffraction...

294

C3TA14913G 4045..4054  

NLE Websites -- All DOE Office Websites (Extended Search)

powder neutron diffraction. The existence of a reversible tetragonal to cubic phase transition was established to occur between room temperature and 400 &20; C, both on heating and...

295

Energy Density Functional for Nuclei and Neutron Stars  

SciTech Connect

Background: Recent observational data on neutron star masses and radii provide stringent constraints on the equation of state of neutron rich matter [ Annu. Rev. Nucl. Part. Sci. 62 485 (2012)]. Purpose: We aim to develop a nuclear energy density functional that can be simultaneously applied to finite nuclei and neutron stars. Methods: We use the self-consistent nuclear density functional theory (DFT) with Skyrme energy density functionals and covariance analysis to assess correlations between observables for finite nuclei and neutron stars. In a first step two energy functionals a high density energy functional giving reasonable neutron properties, and a low density functional fitted to nuclear properties are matched. In a second step, we optimize a new functional using exactly the same protocol as in earlier studies pertaining to nuclei but now including neutron star data. This allows direct comparisons of performance of the new functional relative to the standard one. Results: The new functional TOV-min yields results for nuclear bulk properties (energy, rms radius, diffraction radius, and surface thickness) that are of the same quality as those obtained with the established Skyrme functionals, including SV-min. When comparing SV-min and TOV-min, isoscalar nuclear matter indicators vary slightly while isovector properties are changed considerably. We discuss neutron skins, dipole polarizability, separation energies of the heaviest elements, and proton and neutron drip lines. We confirm a correlation between the neutron skin of 208Pb and the neutron star radius. Conclusions: We demonstrate that standard energy density functionals optimized to nuclear data do not carry information on the expected maximum neutron star mass, and that predictions can only be made within an extremely broad uncertainty band. For atomic nuclei, the new functional TOV-min performs at least as well as the standard nuclear functionals, but it also reproduces expected neutron star data within assumed error bands. This functional is expected to yield more reliable predictions in the region of very neutron rich heavy nuclei.

Erler, J. [UTK/ORNL/German Cancer Research Center-Heidelberg; Horowitz, C. J. [UTK/ORNL/Indiana University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw; Rafalski, M. [UTK/ORNL; Reinhard, P.-G. [Universitat Erlangen, Germany

2013-01-01T23:59:59.000Z

296

Location of Cu2+ in CHA zeolite investigated by X-ray diffraction using the Rietveld/maximum entropy method  

Science Journals Connector (OSTI)

Rietveld/MEM analysis applied to synchrotron powder X-ray diffraction data of dehydrated CHA zeolites with catalytically active Cu2+ reveals Cu2+ in both the six- and eight-membered rings in the CHA framework, providing the first complete structural model that accounts for all Cu2+. Density functional theory calculations are used to corroborate the experimental structure and to discuss the Cu2+ coordination in terms of the Al distribution in the framework.

Andersen, C.W.

2014-09-23T23:59:59.000Z

297

Characterization of Ni/Al multilayer on Si substrate by diffraction and reflectometry techniques  

SciTech Connect

An ion beam deposited multilayer film of nominal thickness [Ni(200 Angst )/Al(100 Angst )]x5 on Si substrate has been characterized by X-Ray Diffraction(XRD), X-Ray Reflectivity (XRR) and Polarized neutron reflectivity(PNR). The present paper attempts to identify presence of any intermetallic compounds at the interfaces of the as-deposited sample. Structural parameters obtained from XRR and PNR are close to design values.

Swain, Mitali; Basu, Saibal; Bhattacharya, Debarati; Gupta, Mukul [Solid State Physics Division Bhabha Atomic Research Center, Mumbai 400085 (India); UGC-DAE-Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

2012-06-05T23:59:59.000Z

298

Solid state neutron detector and method for use  

DOE Patents (OSTI)

Crystals of lithium tetraborate or alpha-barium borate had been found to be neutron detecting materials. The crystals are prepared using known crystal growing techniques, wherein the process does not include the common practice of using a fluxing agent, such as sodium oxide or sodium fluoride, to reduce the melting temperature of the crystalline compound. Crystals prepared by this method can be sliced into thin single or polycrystalline wafers, or ground to a powder and prepared as a sintered compact or a print paste, and then configured with appropriate electronic hardware, in order to function as neutron detectors.

Doty, F. Patrick (Livermore, CA); Zwieback, Ilya (New Milford, NJ); Ruderman, Warren (Demarest, NJ)

2002-01-01T23:59:59.000Z

299

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

300

Modelling the mechanical behaviour of pharmaceutical powders during compaction  

E-Print Network (OSTI)

are made of dry powder through a powder compaction process. In the pharmaceutical industry, billionsModelling the mechanical behaviour of pharmaceutical powders during compaction C.-Y. Wua,T, O.M. Ruddyb , A.C. Benthamb , B.C. Hancockc , S.M. Besta , J.A. Elliotta a Pfizer Institute for Pharmaceutical

Elliott, James

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Direct Measurement of Neutron?Neutron Scattering  

Science Journals Connector (OSTI)

In order to resolve long?standing discrepancies in indirect measurements of the neutron?neutron scattering length ann and contribute to solving the problem of the charge symmetry of the nuclear force the collaboration DIANNA (Direct Investigation of ann Association) plans to measure the neutron?neutron scattering cross section ? nn . The key issue of our approach is the use of the through?channel in the Russia reactor YAGUAR with a peak neutron flux of 1018 /cm2/s. The proposed experimental setup is described. Results of calculations are presented to connect ? nn with the nn?collision detector count rate and the neutron flux density in the reactor channel. Measurements of the thermal neutron fields inside polyethylene converters show excellent prospects for the realization of the direct nn?experiment.

E. I. Sharapov; C. D. Bowman; B. E. Crawford; W. I. Furman; C. R. Howell; B. G. Levakov; V. I. Litvin; W. I. Lychagin; A. E. Lyzhin; E. P. Magda; G. E. Mitchell; G. V. Muzichka; G. V. Nekhaev; Yu. V. Safronov; V. N. Shvetsov; S. L. Stephenson; A. V. Strelkov; W. Tornow

2003-01-01T23:59:59.000Z

302

Neutron-Mirror-Neutron Oscillations in a Trap  

E-Print Network (OSTI)

We calculate the rate of neutron-mirror-neutron oscillations for ultracold neutrons trapped in a storage vessel. Recent experimental bounds on the oscillation time are discussed.

B. Kerbikov; O. Lychkovskiy

2008-04-03T23:59:59.000Z

303

Neutronmirror-neutron oscillations in a trap  

Science Journals Connector (OSTI)

We calculate the rate of neutronmirror-neutron oscillations for ultracold neutrons trapped in a storage vessel. Recent experimental bounds on the oscillation time are discussed.

B. Kerbikov and O. Lychkovskiy

2008-06-27T23:59:59.000Z

304

Manuel Lujan Jr. Neutron Scattering Center Los Alamos Neutron...  

NLE Websites -- All DOE Office Websites (Extended Search)

2013 LANSCE School on Neutron Scattering Geosciences & Materials in Extreme Environments Manuel Lujan Jr. Neutron Scattering Center Los Alamos Neutron Science Center Los Alamos...

305

Recent Results in Diffractive ep Scattering at HERA  

E-Print Network (OSTI)

Recent Results in Diffractive ep Scattering at HERA Introduction to diffraction in ep Exclusive Diffraction in ep Scattering Matthew Beckingham 2 Diffraction Lepton-hadron (-p) or hadron-hadron (p to interpret in (p)QCD? #12;Lake Louise 06 Diffraction in ep Scattering Matthew Beckingham 3 Diffraction

306

Preliminary study of neutron absorption by concrete with boron carbide addition  

SciTech Connect

Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates the most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.

Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat; Ahmad, Megat Harun Al Rashid Megat; Yazid, Hafizal [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Ariffin, Fatin Nabilah Tajul; Ahmad, Sahrim [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Hamid, Roszilah [Department of Civil and Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Mohamed, Abdul Aziz [College of Engineering, Universiti Tenaga National, Jalan Ikram-Uniten, 43000 Kajang, Selangor (Malaysia)

2014-02-12T23:59:59.000Z

307

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

Free flowing, conformable powder-like mix of silica particles and a phase change material (pcm) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 10 figures.

Salyer, I.O.

1993-10-19T23:59:59.000Z

308

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

A free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7 [times] 10[sup [minus]3] to about 7 [times] 10[sup [minus]2] microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 9 figs.

Salyer, I.O.

1992-04-21T23:59:59.000Z

309

EPR Investigation of Irradiated Curry Powder  

SciTech Connect

Gamma-ray irradiated curry powder, a well priced oriental spice was investigated in order to establish the ability of EPR to detect the presence and time stability of free irradiation free-radicals. Accordingly, curry powder aliquots were irradiated with gradually increasing absorbed doses up to 11.3 kGy. The EPR spectra of all irradiated samples show the presence of al last two different species of free radicals, whose concentration increased monotonously with the absorbed doses. A 100 deg. C isothermal annealing of irradiated samples has shown a differential reduction of amplitude of various components of the initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after more than one year storage at room temperature, all of them being very useful in establishing the existence of any previous irradiation treatment.

Duliu, O. G.; Ali, S. I. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Bucharest (Romania); Georgescu, R. [National Institute for Physics and Nuclear Engineering-Horia Hulubei, P.O. Box MG-6, 077125 Bucharest (Romania)

2007-04-23T23:59:59.000Z

310

Powder River Energy Corporation | Open Energy Information  

Open Energy Info (EERE)

Jump to: navigation, search Jump to: navigation, search Name Powder River Energy Corporation Place Sundance, Wyoming Website precorp.coop/ Utility Id 19156 Utility Location Yes Ownership C NERC Location WECC Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] SGIC[2] Energy Information Administration Form 826[3] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Powder River Energy Corporation Smart Grid Project was awarded $2,554,807 Recovery Act Funding with a total project value of $5,109,614. Utility Rate Schedules Grid-background.png General Service (GS)-Single Phase Commercial General Service (GS)-Three phase Commercial General Service-Coal Bed Methane (GS-CBM)-Single Phase Commercial

311

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the p.c.m. must be added to the silica in an amount of 80 wt. % or less p.c.m. per combined weight of silica and p.c.m. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a p.c.m. material. The silica-p.c.m. mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, I.O.

1993-05-18T23:59:59.000Z

312

Dry powder mixes comprising phase change materials  

DOE Patents (OSTI)

Free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 2 figures.

Salyer, I.O.

1994-02-01T23:59:59.000Z

313

High mass diffraction at the LHC  

E-Print Network (OSTI)

We use a Monte Carlo implementation of recently developped models of exclusive diffractive W, top, Higgs and stop productions to assess the sensitivity of the LHC experiments.

C. Royon

2005-07-08T23:59:59.000Z

314

Encircled energy of diffracted converging spherical waves  

Science Journals Connector (OSTI)

We studied the diffraction phenomenon of a circular aperture that was illuminated by a monochromatic converging spherical wave. The theoretical part of this study was based on the...

Li, Yajun

1983-01-01T23:59:59.000Z

315

Numerical Simulation of Aerated Powder Consolidation1  

E-Print Network (OSTI)

applications. Typically a powder is stored in a bunker or silo, see Figure 1. During filling, air gets trapped of the container are neglected, in effect, treating only the case of cylindrical bunkers. In [4], that case. 1 #12;H(t) z bunker top surface z A(z) = R(z) 2 A(z+ z) = R(z+ z) 2 FIG. 1. Geometry and coordinate

316

Numerical Simulation of Aerated Powder Consolidation 1  

E-Print Network (OSTI)

applications. Typically a powder is stored in a bunker or silo, see Figure 1. During filling, air gets trapped of the container are neglected, in effect, treating only the case of cylindrical bunkers. In [4], that case. 1 #12; 2 K.A. KRISTY AND P.A. GREMAUD H(t) z bunker top surface dz A(z) = R(z) p 2 A(z+ z) = R(z+ z

317

Neutron crystallography aids drug design  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron crystallography aids drug design Neutron crystallography aids drug design Researchers have used neutron crystallography for the first time to determine the structure of a...

318

Los Alamos Neutron Science Center  

NLE Websites -- All DOE Office Websites (Extended Search)

LINAC Outreach Affiliations Visiting LANSCE Facilities Isotope Production Facility Lujan Neutron Scattering Center MaRIE Proton Radiography Ultracold Neutrons Weapons Neutron...

319

Surface Studies by Low-Energy Electron Diffraction and Reflection High-Energy-Electron Diffraction  

Science Journals Connector (OSTI)

In this chapter, we present the basic concepts of the low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED) experiments. The main goal is to provide an overview of the ...

P. Laukkanen; J. Sadowski; M. Guina

2012-01-01T23:59:59.000Z

320

Neutron range spectrometer  

DOE Patents (OSTI)

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

Manglos, Stephen H. (East Syracuse, NY)

1989-06-06T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Neutron Generator as a Neutron Source for BNCT  

Science Journals Connector (OSTI)

A neutron generator was investigated for a neutron source for BNCT. Neutron generators have some obvious advantages over nuclear reactors for this purpose. The neutron source is the reaction D(d,n)3He. Moderation...

Gad Shani; Lev Tsvang; Semion Rozin; Michael Quastel

1996-01-01T23:59:59.000Z

322

Large aperture diffractive space telescope  

DOE Patents (OSTI)

A large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary objective lens functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass "aiming" at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The objective lens includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the objective lens, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets which may be either earth bound or celestial.

Hyde, Roderick A. (Livermore, CA)

2001-01-01T23:59:59.000Z

323

Diffractive parton distributions from H1 data  

E-Print Network (OSTI)

We analyse the latest H1 large rapidity gap data to obtain diffractive parton distributions, using a procedure based on perturbative QCD, and compare them with distributions obtained from the simplified Regge factorisation type of analysis. The diffractive parton densities and structure functions are made publicly available.

Martin, A D; Watt, G

2007-01-01T23:59:59.000Z

324

Diffractive parton distributions from H1 data  

E-Print Network (OSTI)

We analyse the latest H1 large rapidity gap data to obtain diffractive parton distributions, using a procedure based on perturbative QCD, and compare them with distributions obtained from the simplified Regge factorisation type of analysis. The diffractive parton densities and structure functions are made publically available.

A. D. Martin; M. G. Ryskin; G. Watt

2006-09-26T23:59:59.000Z

325

Ultrasonic imaging with limited-diffraction beams  

E-Print Network (OSTI)

Limited-diffraction beams are a class of waves that may be localized in space and time. Theoretically, these beams are propagation invariant and can propagate to an infinite distance without spreading. In practice, when these beams are produced with wave sources of a finite aperture and energy, they have a very large depth of field, meaning that they can keep a small beam width over a large distance. Because of this property, limited-diffraction beams may have applications in various areas such as medical imaging and tissue characterization. In this paper, fundamentals of limited-diffraction beams are reviewed and the studies of these beams are put into a unified theoretical framework. Theory of limited-diffraction beams is further developed. New limited-diffraction solutions to Klein-Gordon Equation and Schrodinger Equation, as well as limited-diffraction solutions to these equations in confined spaces are obtained. The relationship between the transformation that converts any solutions to an (-1)-dimensional wave equation to limited-diffraction solutions of an -dimensional equation and the Lorentz transformation is clarified and extended. The transformation is also applied to the Klein-Gordon Equation. In addition, applications of limited-diffraction beams are summarized.

Jian-yu Lu

2006-03-28T23:59:59.000Z

326

Novel features of diffraction at the LHC  

Science Journals Connector (OSTI)

Interest and problems in the studies of diffraction at LHC are highlighted. Predictions for the global characteristics of protonproton interactions at the LHC energy are given. Potential discoveries of the antishadow scattering mode which is allowed in principle by unitarity and diffractive scattering conjugated with high-ET jets are discussed.

V A Petrov; A V Prokudin; S M Troshin; N E Tyurin

2001-01-01T23:59:59.000Z

327

Experimental evaluation of neutron performance in boron-doped low activation concrete  

Science Journals Connector (OSTI)

......concrete (LAC) without boron-doping exposed to reactor...and special limestone. Boron (0.8 wt.%) was introduced in the form of boron carbide. NaCl powder...counted twice to detect two isotopes, 97Zr and 95Zr. The...uncertainty in neutron spectra determination is independent from uncertainties......

T. Ogawa; M. N. Morev; T. Abe; T. Iimoto; T. Kosako; K. Kimura; M. Kinno

2010-06-01T23:59:59.000Z

328

Neutron producing target for accelerator based neutron source for  

E-Print Network (OSTI)

247 Neutron producing target for accelerator based neutron source for NCT V. Belov1 , S. Fadeev1, Russia Summary Neutron producing targets for novel accelerator based neutron source [1, 2] are presented Neutron producing target is one of the main elements of proposed accelerator based facility for neutron

Taskaev, Sergey Yur'evich

329

Defining Electron Backscatter Diffraction Resolution  

SciTech Connect

Automated electron backscatter diffraction (EBSD) mapping systems have existed for more than 10 years [1,2], and due to their versatility in characterizing multiple aspects of microstructure, they have become an important tool in microscale crystallographic studies. Their increasingly widespread use however raises questions about their accuracy in both determining crystallographic orientations, as well as ensuring that the orientation information is spatially correct. The issue of orientation accuracy (as defined by angular resolution) has been addressed previously [3-5]. While the resolution of EBSD systems is typically quoted to be on the order of 1{sup o}, it has been shown that by increasing the pattern quality via acquisition parameter adjustment, the angular resolution can be improved to sub-degree levels. Ultimately, the resolution is dependent on how it is identified. In some cases it can be identified as the orientation relative to a known absolute, in others as the misorientation between nearest neighbor points in a scan. Naturally, the resulting values can be significantly different. Therefore, a consistent and universal definition of resolution that can be applied to characterize any EBSD system is necessary, and is the focus of the current study. In this work, a Phillips (FEI) XL-40 FEGSEM coupled to a TexSEM Laboratories OIM system was used. The pattern capturing hardware consisted of both a 512 by 512 pixel SIT CCD camera and a 1300 by 1030 pixel Peltier cooled CCD camera. Automated scans of various sizes, each consisting of 2500 points, were performed on a commercial-grade single crystal silicon wafer used for angular resolution measurements. To adequately quantify angular resolution for all possible EBSD applications we define two angular values. The first is {omega}{sub center}, the mean of the misorientation angle distribution between all scan points and the scan point coincident to the calibration source (typically the scan center). The {omega}{sub center} value is used to describe the overall system resolution, as it effectively quantifies the deviation of all orientations in the scan relative to the diffraction pattern least affected by distortions. The second is {omega}{sub max}, the largest misorientation angle possible between any pair of points in the dataset, and describes the worst possible case. Fig. 1 shows the effects of scan size and captured pattern resolution (bin size) on both angular values, illustrating that smaller scan and bin sizes have the effect of increasing angular resolution. However, it can be observed that the benefits of utilizing smaller bin sizes (and consequently slower data collection) diminish with scan size. Fig. 2 shows the effect of the number of pixels used in the Hough transform (defined as the ratio of pixels used to maximum possible pixels) on the angular values. It can be seen that the best angular resolutions are achieved at a pixel ratio of 0.80, again illustrating that the use of higher resolutions is not always beneficial. As evidenced by the results, the use of {omega}{sub center} and {omega}{sub max} not only permits the characterization of the angular resolution of an EBSD system, but they allow for a more efficient utilization of the system by identifying appropriate settings depending on the desired angular resolution [6].

El-Dasher, B S; Rollett, A D

2005-02-07T23:59:59.000Z

330

Mechanochemical synthesis of tungsten carbide nano particles by using WO{sub 3}/Zn/C powder mixture  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Nano particles of WC are synthesized by mechanochemical process. ? Zn was used to reduce WO{sub 3}. ? By removing ZnO from the milling products with an acid leaching, WC will be the final products. ? XRD results showed that the reduction reactions were completed after 36 h. ? TEM and SEM images showed that the morphology of produced powder is nearly spherical like. -- Abstract: In this research we introduce a new, facile, and economical system for fabrication of tungsten carbide (WC) nano particle powder. In this system WO{sub 3}, Zn, and C have been ball-milled for several hours, which led to the synthesis of tungsten carbide nano particles. The synthesized WC can successfully be separated from the ball-milled product by subjecting the product powder to diluted HCl for removing ZnO and obtaining WC. X-ray diffraction (XRD) analysis indicates that the reduction of WO{sub 3} will be completed gradually by increasing milling time up to 36 h. Scanning electron microscope (SEM), and transmission electron microscope (TEM) images show that after 36 h of milling the particle size of the fabricated powder is nano metric (about 20 nm). Results have shown that this system can surmount some main problems occurred in previous similar WC synthesizing systems. For example carbothermic reduction reactions, which lead to the synthesis of W{sub 2}C instead of WC, would not be activated because in this system reactions take place gradually.

Hoseinpur, Arman, E-mail: arman.hoseinpur@stu-mail.um.ac.ir [Department of Materials and Metallurgical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Islamic Republic of Iran (Iran, Islamic Republic of)] [Department of Materials and Metallurgical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Islamic Republic of Iran (Iran, Islamic Republic of); Vahdati Khaki, Jalil; Marashi, Maryam Sadat [Department of Materials and Metallurgical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Islamic Republic of Iran (Iran, Islamic Republic of)] [Department of Materials and Metallurgical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Islamic Republic of Iran (Iran, Islamic Republic of)

2013-02-15T23:59:59.000Z

331

Instruments | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

NScD Careers NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Instruments SHARE Instruments at SNS and HFIR SNS Instrument Name HFIR Instrument Name 1B NOMAD - Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS - Backscattering Spectrometer CG-1D IMAGING - Neutron Imaging Prototype Facility 3 SNAP - Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer 4A MR - Magnetism Reflectometer CG-3 Bio-SANS - Biological Small-Angle Neutron Scattering Instrument 4B LR - Liquids Reflectometer CG-4C CTAX - Cold Neutron Triple-Axis Spectrometer 5 CNCS - Cold Neutron Chopper Spectrometer HB-1 PTAX - Polarized Triple-Axis Spectrometer

332

Neutron dose equivalent meter  

DOE Patents (OSTI)

A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

Olsher, Richard H. (Los Alamos, NM); Hsu, Hsiao-Hua (Los Alamos, NM); Casson, William H. (Los Alamos, NM); Vasilik, Dennis G. (Los Alamos, NM); Kleck, Jeffrey H. (Menlo Park, CA); Beverding, Anthony (Foster City, CA)

1996-01-01T23:59:59.000Z

333

Pulsed-neutron monochromator  

DOE Patents (OSTI)

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, H.A. Jr.

1984-01-01T23:59:59.000Z

334

The Harwell Neutron Project  

Science Journals Connector (OSTI)

... 2 cm. thick, placed on three sides of the neutron booster. A layer of boron-10 metal placed between these tanks and the uranium-235 core prevents return of slow neutrons ...

M. J. POOLE; E. R. RAE

1960-01-30T23:59:59.000Z

335

Pulsed-neutron monochromator  

DOE Patents (OSTI)

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, Jr., Herbert A. (Oak Ridge, TN)

1985-01-01T23:59:59.000Z

336

Neutrons - 88-Inch Cyclotron  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutrons Neutron beams are available at the 88-Inch Cyclotron. Available energies range of from 8 to 30 MeV, with fluxes of up to 1E8 neutronscm2sec. For more information,...

337

Thermal Neutron Scattering  

Science Journals Connector (OSTI)

... of its title. It is not for the nuclear physicist, nor even for the neutron physicist, but for the student of solids and liquids. "Thermal ... physicist, but for the student of solids and liquids. "Thermal neutron ...

G. E. BACON

1968-11-09T23:59:59.000Z

338

Neutron activation analysis  

Science Journals Connector (OSTI)

Neutron activation analysis (NAA) is an that relies on the measurement of ?-rays emitted from a sample that was irradiated by neutrons. The rate at which ?-rays are emitted from an element in a sample is dir...

James R. Budahn

1998-01-01T23:59:59.000Z

339

Ultrafast neutron detector  

DOE Patents (OSTI)

A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

Wang, C.L.

1985-06-19T23:59:59.000Z

340

Effective temperature of an aging powder  

Science Journals Connector (OSTI)

The aging dynamics and the fluctuation-dissipation relation between the spontaneous diffusion induced by a random noise and the drift motion induced by a small stirring force are numerically investigated in a 3D schematic model of compacting powder: a gravity-driven lattice-gas with purely kinetic constraints. The compaction dynamics is characterized by a super-aging behavior and, in analogy with glasses, exhibits a purely dynamical time-scale-dependent effective temperature. A simple experiment to measure this quantity is suggested.

Mauro Sellitto

2001-05-11T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Nanocrystalline carbon coatings and powders for medicine  

Science Journals Connector (OSTI)

All the allotropic forms of carbon, i.e., diamond, graphite and carbine, find applications in different areas of medicine, but diamond is specifically preferred. The unique properties of thin diamond layers, due to the highest biocompatibility of carbon resulting from the presence of this element in human body, make them candidates for producing biomaterials. Especially carbon in the form of a nanocrystalline diamond film has found industrial applications in the area of medical implants. Diamond Powder Particles (DPP), as an extended surface NCD, are useful for medical examinations. Different medical implants are covered with Nanocrystalline Diamond Coatings (NCD). NCD forms a diffusion barrier between implant and human environment.

Katarzyna Mitura; Anna Karczemska; Piotr Niedzielski; Jacek Grabarczyk; Witold Kaczorowski; Petr Louda; Stanislaw Mitura

2008-01-01T23:59:59.000Z

342

Laser production of articles from powders  

DOE Patents (OSTI)

Method and apparatus for forming articles from materials in particulate form in which the materials are melted by a laser beam and deposited at points along a tool path to form an article of the desired shape and dimensions. Preferably the tool path and other parameters of the deposition process are established using computer-aided design and manufacturing techniques. A controller comprised of a digital computer directs movement of a deposition zone along the tool path and provides control signals to adjust apparatus functions, such as the speed at which a deposition head which delivers the laser beam and powder to the deposition zone moves along the tool path.

Lewis, Gary K. (Los Alamos, NM); Milewski, John O. (Santa Fe, NM); Cremers, David A. (Los Alamos, NM); Nemec, Ronald B. (White Rock, NM); Barbe, Michael R. (White Rock, NM)

1998-01-01T23:59:59.000Z

343

Biology and Soft Matter Division - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Home › Neutron Sciences Directorate › Biology and Soft Matter Division Home › Neutron Sciences Directorate › Biology and Soft Matter Division Biology and Soft Matter Division Paul Langan, BSMD Director BSMD Director Paul Langan. The Biology and Soft Matter Division (BSMD) operates an external user program for biological and soft matter research using neutron techniques at SNS and HFIR. Division personnel enable the research initiated by external users by acting as instrument responsible scientists and local contacts on a range of different beam lines. BSMD works closely with the Center for Structural Molecular Biology. Diffraction, small-angle scattering, and reflectometry are ideal methods for studying structure and organization from the atomic to the micron length scales, and neutron spectroscopic methods characterize self and

344

Neutron computed tomography  

E-Print Network (OSTI)

to make the Donner Algorithms run. TABLE OF CONTEliiTS CHAPTF. . R I NEI. TRON RADIOGRAPHY . I. 1 Background . I. 2 Theory . l. 3 Neutron Beam Characterization I. 4 Image Detectors . COMPI'TED TOMOGRAPHY . Il I Background . II. 2 Notation II. 3... data which is generated by rays traveling (and being attenuated) in straight lines. However in neutron radiography, what is measured is, to most extents, the levels of neutrons which are not attenuated. Neutrons are particles. They scatter...

Russell, Clifford Marlow

2012-06-07T23:59:59.000Z

345

Neutron scattering and ribosomes  

Science Journals Connector (OSTI)

... the complexity of intra-ribosomal interactions. This is however by no means the case with neutron ...neutronscattering ...

Richard Brimacombe

1977-06-23T23:59:59.000Z

346

More about neutron - mirror neutron oscillation  

E-Print Network (OSTI)

It was pointed out recently that oscillation of the neutron $n$ into mirror neutron $n'$, a sterile twin of the neutron with exactly the same mass, could be a very fast process with the the baryon number violation, even faster than the neutron decay itself. This process is sensitive to the magnetic fields and it could be observed by comparing the neutron lose rates in the UCN storage chambers for different magnetic backgrounds. We calculate the probability of $n-n'$ oscillation in the case when a mirror magnetic field $\\vec{B}'$ is non-zero and show that in this case it can be suppressed or resonantly enhanced by applying the ordinary magnetic field $\\vec{B}$, depending on its strength and on its orientation with respect to $\\vec{B}'$. The recent experimental data, under this hypothesis, still allow the $n-n'$ oscillation time order 1 s or even smaller. Moreover, they indicate that the neutron losses are sensitive to the orientation of the magnetic field. %at about $3\\sigma$ level. If these hints will be confirmed in the future experiments, this would point to the presence of the mirror magnetic field on the Earth of the order of 0.1 G, or some equivalent spin-dependent force of the other origin that makes a difference between the neutron and mirror neutron states.

Zurab Berezhiani

2008-04-13T23:59:59.000Z

347

Neutron removal cross section as a measure of neutron skin  

Science Journals Connector (OSTI)

We study the relation between neutron removal cross section (?-N) and neutron skin thickness for finite neutron-rich nuclei using the statistical abrasion ablation model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between ?-N and the neutron skin thickness for neutron-rich nuclei. Further analysis suggests that the relative increase of neutron removal cross section could be used as a quantitative measure for neutron skin thickness in neutron-rich nuclei.

D. Q. Fang (???); Y. G. Ma (???); X. Z. Cai (???); W. D. Tian (???); H. W. Wang (???)

2010-04-07T23:59:59.000Z

348

The neutron warhead decision  

Science Journals Connector (OSTI)

The neutron warhead decision ... Nuclear war moved a step closer last week with the U.S.'s decision to move ahead with production of so-called neutron warheads for use on short-range missiles and in artillery shells. ... And neutron weapons would be almost as effective on ... ...

MICHAEL HEYLIN

1981-08-17T23:59:59.000Z

349

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

DOE Patents (OSTI)

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

Park, Jong-Hee (Clarendon Hills, IL)

2011-11-29T23:59:59.000Z

350

Iowa Powder Atomization Technologies, Inc. | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Iowa Powder Iowa Powder Atomization Technologies, Inc. America's Next Top Energy Innovator Challenge 6067 likes Iowa Powder Atomization Technologies, Inc. Ames Laboratory Iowa Powder Atomization Technologies, Inc. (IPAT) aims to become a leading domestic titanium powder producer allowing for a paradigm shift in the cost of titanium powders for metal injection molding (MIM) feedstock. Decreasing this cost will create vast opportunities for aerospace, military, biomedical, and consumer applications. Titanium and its fabrication by MIM can become one of the United States' most advanced processing technologies and help jump-start many corresponding manufacturing sectors, spurring job creation and economic growth throughout the United States. Titanium is viewed as one of the most strategic metals of our future. Its

351

Visualizations of the Exclusive Central Diffraction  

E-Print Network (OSTI)

The case of the low invariant mass exclusive central diffractive production is considered in the general theoretical framework. It is shown that diffractive patterns (differential cross-sections on variables like transfer momenta squared, the azimuthal angle between final hadrons and their combinations) can serve as a unique tool to explore the picture of the $pp$ interaction and falsify theoretical models. Basic kinematical and dynamical properties of the process are considered in detail. As an example, visualizations of diffractive patterns in the model with three pomerons for processes $p+p\\to p+R+p$ and $p+p\\to p+\\pi^{+}\\pi^{-}+p$ are presented.

R. A. Ryutin

2014-09-19T23:59:59.000Z

352

Synthesis of nanophase W and WC powders from ammonium metatungstate  

SciTech Connect

Nanophase {alpha}-W powder has been synthesized by reductive decomposition of ammonium metatungstate (AMT) at low temperatures (< 600 C). The formation of {beta}-W, which is the usual product of low temperature reduction of tungsten oxides, is avoided. Thus, it has been possible to lower the carburization temperature of W to WC to about 575 C. Nanophase WC powder (< 10 nm grain size) is produced by the low temperature carburization of nanophase {alpha}-W powder.

Gao, L.; Kear, B.H. [Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States). Dept. of Ceramic Engineering

1996-06-01T23:59:59.000Z

353

Published Research 2009 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

9 9 Most publications are in Adobe Portable Document Format. Download Adobe Reader. For more information about any of these publications, please contact the Neutrons Sciences Communications Office. Primary Author Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Abdou A., Wendel M., Felde D., Riemer B., "CFD validation of gas injection in flowing mercury over vertical smooth and grooved wall", Proceedings of the ASME Fluids Engineering Division Summer Conference 2009. Agamalian M., Carpenter J. M., Richardson J. W., "Validity of the Darwin and Ewald reflectivity functions in the range of the far wings: neutron diffraction study", Physics Letters A 373, 292-295. Alfonsov A., Vavilova E., Kataev V., Buchner B., Podlesnyak A., Russina M., Furrer A., Strassle Th., Pomjakushina E., Conder K., Khomskii

354

Published Research 2009 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

09 09 Published Research 2009 Most publications are in Adobe Portable Document Format. Download Adobe Reader. For more information about any of these publications, please contact the Neutrons Sciences Communications Office. Primary Author Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A A. Abdou, M. Wendel, D. Felde, and B. Riemer, "CFD validation of gas injection in flowing mercury over vertical smooth and grooved wall," Proceedings of the ASME Fluids Engineering Division Summer Conference 2009, FEDSM2009 1 (Part B), 1061-1067 (2009). M. Agamalian, J. M. Carpenter, and J. W. Richardson, "Validity of the Darwin and Ewald reflectivity functions in the range of the far wings: Neutron diffraction study." Physics Letters A 373, 292-295 (2009). A. Alfonsov, E. Vavilova, V. Kataev, B. Büchner, A. Podlesnyak, M.

355

Published Research 2006 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

6 6 Most publications are in Adobe Portable Document Format. Download Adobe Reader. For more information about any of these publications, please contact the Neutrons Sciences Communications Office. Primary Author Index: B C E F G H I J K L M N O P R S T W X Y B E. D. Bauer, A. D. Christianson, J. S. Gardner, V. A. Sidorov, J. D. Thompson, J. L. Sarrao, and M. F. Hundley, "Physical properties of the ferromagnetic heavy-fermion compound UIr2Zn20," Physical Review B 74, (Oct 2006). B. Bennett, P. Langan, L. Coates, M. Mustyakimov, B. Schoenborn, E.E. Howell, C. Dealwis, "Neutron diffraction studies of Escherichia coli dihydrofolate reductase complexed with methotrexate," PNAS of the United States of America 103(49), pp. 18493-8 (5 Dec. 2006). M. L. Benson, P. K. Liaw, H. Choo, T. A. Saleh, D. W. Brown, M. R.

356

Forming gas treatment of lithium ion battery anode graphite powders  

DOE Patents (OSTI)

The invention provides a method of making a battery anode in which a quantity of graphite powder is provided. The temperature of the graphite powder is raised from a starting temperature to a first temperature between 1000 and 2000.degree. C. during a first heating period. The graphite powder is then cooled to a final temperature during a cool down period. The graphite powder is contacted with a forming gas during at least one of the first heating period and the cool down period. The forming gas includes H.sub.2 and an inert gas.

Contescu, Cristian Ion; Gallego, Nidia C; Howe, Jane Y; Meyer, III, Harry M; Payzant, Edward Andrew; Wood, III, David L; Yoon, Sang Young

2014-09-16T23:59:59.000Z

357

COAL QUALITY AND GEOCHEMISTRY, POWDER RIVER BASIN, WYOMING AND MONTANA  

E-Print Network (OSTI)

in the Powder River Basin in Wyoming and Montana (fig. PQ-1) is considered to be "clean coal." For the location

358

Joining of parts via magnetic heating of metal aluminum powders  

DOE Patents (OSTI)

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

Baker, Ian

2013-05-21T23:59:59.000Z

359

Process for synthesizing compounds from elemental powders and product  

DOE Patents (OSTI)

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

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

1993-01-01T23:59:59.000Z

360

High energy neutron dosimeter  

DOE Patents (OSTI)

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

Rai, K.S.F.

1994-01-11T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Principles of neutron reflection  

SciTech Connect

Neutron reflection is perhaps the most developed branch of slow neutrons optics, which in itself is a direct consequence of the undulatory nature of the neutron. After reviewing the basic types of interactions (nuclear and magnetic) between neutrons and matter, the formalism is introduced to calculate the reflectivity from a sample composed of stacked flat layers and, inversely, to calculate the stacking from reflectivity measurements. Finally, a brief survey of the applications of neutron reflection is given, both in technology and in fundamental research. 32 refs., 6 figs.

Felcher, G.P.

1988-08-01T23:59:59.000Z

362

On neutron numbers and atomic masses  

Science Journals Connector (OSTI)

On neutron numbers and atomic masses ... Assigning neutron numbers, correct neutron numbers, and atomic masses and nucleon numbers. ...

R. Heyrovsk

1992-01-01T23:59:59.000Z

363

Phenomenology of single and double diffraction dissociation  

E-Print Network (OSTI)

Predictions of the gap-probability renormalization model for single and double diffraction dissociation cross sections in proton-proton collisions at the LHC are presented and compared with recent CMS measurements.

Konstantin Goulianos

2013-10-21T23:59:59.000Z

364

Diffractive parton distributions from perturbative QCD  

E-Print Network (OSTI)

The asymptotic collinear factorisation theorem, which holds for diffractive deep-inelastic scattering, has important modifications in the sub-asymptotic HERA regime. We use perturbative QCD to quantify these modifications. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation. We emphasise that it is necessary to include both the gluonic and sea-quark t-channel components of the perturbative Pomeron. The corresponding Pomeron-to-parton splitting functions are derived in the Appendix.

Martin, A D; Watt, G

2005-01-01T23:59:59.000Z

365

Diffractive parton distributions from perturbative QCD  

E-Print Network (OSTI)

The asymptotic collinear factorisation theorem, which holds for diffractive deep-inelastic scattering, has important modifications in the sub-asymptotic HERA regime. We use perturbative QCD to quantify these modifications. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation. We emphasise that it is necessary to include both the gluonic and sea-quark t-channel components of the perturbative Pomeron. The corresponding Pomeron-to-parton splitting functions are derived in the Appendix.

A. D. Martin; M. G. Ryskin; G. Watt

2005-04-15T23:59:59.000Z

366

Nuclear diffractive structure functions at high energies  

E-Print Network (OSTI)

A future high-energy electron-ion collider would explore the non-linear weakly-coupled regime of QCD, and test the Color Glass Condensate (CGC) approach to high-energy scattering. Hard diffraction in deep inelastic scattering off nuclei will provide many fundamental measurements. In this work, the nuclear diffractive structure function F_{2,A}^D is predicted in the CGC framework, and the features of nuclear enhancement and suppression are discussed.

C. Marquet; H. Kowalski; T. Lappi; R. Venugopalan

2008-05-30T23:59:59.000Z

367

Diffractive photon production at the LHC  

Science Journals Connector (OSTI)

In this paper we study photon production in single and double diffractive processes considering the resolved pomeron model. We estimate the rapidity and transverse momentum dependence of the cross section for the diffractive double photon and photon+jet production. A comparison with the inclusive production is presented. We predict large values for the total cross sections, which make the experimental analysis of these observables feasible at LHC energies.

C. Brenner Mariotto and V. P. Goncalves

2013-10-22T23:59:59.000Z

368

Spallation Neutron Source, SNS  

NLE Websites -- All DOE Office Websites (Extended Search)

Spallation Neutron Source Spallation Neutron Source Providing the most intense pulsed neutron beams in the world... Accumulator Ring Commissioning Latest Step for Spallation Neutron Source The Spallation Neutron Source, located at Oak Ridge National Laboratory, has passed another milestone on the way to completion this year--the commissioning of the proton accumulator ring. Brookhaven led the design and construction of the accumulator ring, which will allow an order of magnitude more beam power than any other facility in the world. The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The figure on the right shows a schematic of the accumulator ring and transport beam lines that are being designed and built by Brookhaven

369

The Neutron Lifetime  

E-Print Network (OSTI)

The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and the simplest example of nuclear beta decay. The nucleon vector and axial vector weak coupling constants G_V and G_A determine the neutron lifetime as well as the strengths of weak interaction processes involving free neutrons and protons that are important in astrophysics, cosmology, solar physics and neutrino detection. In combination with a neutron decay angular correlation measurement, the neutron lifetime can be used to determine the first element of the CKM matrix Vud. Unfortunately the two main experimental methods for measuring the neutron lifetime currently disagree by almost 4 sigma. I will present a brief review of the status of the neutron lifetime and prospects for the future.

Wietfeldt, F E

2014-01-01T23:59:59.000Z

370

The Neutron Lifetime  

E-Print Network (OSTI)

The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and the simplest example of nuclear beta decay. The nucleon vector and axial vector weak coupling constants G_V and G_A determine the neutron lifetime as well as the strengths of weak interaction processes involving free neutrons and protons that are important in astrophysics, cosmology, solar physics and neutrino detection. In combination with a neutron decay angular correlation measurement, the neutron lifetime can be used to determine the first element of the CKM matrix Vud. Unfortunately the two main experimental methods for measuring the neutron lifetime currently disagree by almost 4 sigma. I will present a brief review of the status of the neutron lifetime and prospects for the future.

F. E. Wietfeldt

2014-11-13T23:59:59.000Z

371

Imaging and Neutrons - IAN 2006 - Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

SNS Home Saturday, January 11, 2014 SNS Home Saturday, January 11, 2014 Go IAN 2006 Imaging and Neutrons 2006 October 23-25, 2006 Iran Thomas Auditorium Central Laboratory and Office Building Spallation Neutron Source Oak Ridge National Laboratory, Oak Ridge, TN Who Should Attend Synopsis Goals and Expected Outcomes Application Areas Techniques International Advisory Committee Local Organizing Committee Agenda with Presentations NEW Confirmed Speakers Frequently Asked Questions - FAQ Satellite Workshop - Progress in Electron Volt Neutron Spectroscopy eV Worshop Agenda presentations NEW Lodging, Transportation, Bus Schedule Location Directions and Map Registration CLOSED Abstracts, Posters, Contributed Talks Scholarships Sponsors Vendors May Attend Relevant Reports Important Dates Weather Attractions

372

Al-doped ZnO powdered materials: Al solubility limit and IR absorption properties  

Science Journals Connector (OSTI)

Al-doped ZnO powder was synthesized via the Pechini route with a doping rate varying from 1 to 4mol.%. A solubility limit has been estimated under 0.3mol.% of Al using X-ray diffraction refinements. The incorporation of aluminium into the ZnO lattice was investigated by 27Al NMR, which suggests an extremely low amount of Al in a distribution of sites in ZnO. In order to assess the impact of such a low dopant amount, diffuse reflection experiments were performed for a wavelength range from 200 to 2500nm. If the effect of doping was negligible for samples prepared at 850C, annealing at 1200C clearly reveals enhanced IR absorption properties for the doped samples, which are similar whatever be the nominal Al content.

Hlne Serier; Manuel Gaudon; Michel Mntrier

2009-01-01T23:59:59.000Z

373

Effects of grinding on properties of Mg-PSZ ceramics prepared by the surface enrichment of zirconia powders  

SciTech Connect

Commercial grade zirconia powders of mean particle size of 3.21 microns were super-ground in wet condition in alcoholic medium in a Planetary Ball-Mill for 12-hours using a zirconia pot as well as balls, in order to avoid contaminations from the grinding media. Sedigraph analysis data show the mean particle sizes within the range of 0.4 to 0.2 micron. The super-ground zirconia powders were then treated with appropriate acid and alkali solutions in order to enrich the surfaces of zirconia powders. The chemical analysis reports depict the enrichment phenomena of the processed zirconia powders. Magnesium oxide of different mole percentages (3 to 9%) have been incorporated to the above super-ground and enriched zirconia powder and green specimens were prepared by pressing with a suitable pressure of 200 MPa to yield the green compaction density of 3.06 gm/cm{sup 3}. The compacted green specimens were sintered without pressure at 1,480 C in air followed by normal cooling. X-ray diffraction patterns of the above sintered and cooled specimens have confirmed the formation of Mg-PSZ ceramics with 40% tetragonal phase. The sintered PSZ-products have shown very good surface properties but at the cost of transverse rupture strength. The effects of grinding were observed on the above Mg-PSZ ceramics which exhibit very little change in the tetragonal phase even after 30-minutes of grinding with a 60-mesh diamond wheel at a normal pressure of 4 kg/cm{sup 2}.

Deb, S.; Das, S.R. [Central Glass and Ceramics Research Inst., Calcutta (India). Ceramic Processing Section

1995-10-01T23:59:59.000Z

374

Detonation diffraction in a multi-step channel .  

E-Print Network (OSTI)

??This research investigated multiple detonation diffraction events in order to better understand the limits and benefits of diffraction strategies with respect to pulse detonation engine (more)

Juillet, Daniel M.

2010-01-01T23:59:59.000Z

375

Binary high-frequency-carrier diffractive optical elements: electromagnetic theory  

Science Journals Connector (OSTI)

Using rigorous electromagnetic diffraction theory, we evaluate the potential performance and the limitations of coding diffractive optical elements in the form of a...

Noponen, Eero; Turunen, Jari

1994-01-01T23:59:59.000Z

376

Nanoparticle diffraction gratings for DNA detection on photopatterned glass substrates  

E-Print Network (OSTI)

Sendroiu and R. M. Corn: Nanoparticle diffraction gratingsSendroiu and R. M. Corn: Nanoparticle diffraction gratingsthe principle of the nanoparticle-based DNA detection assay

Sendroiu, Luliana E; Corn, Robert M

2008-01-01T23:59:59.000Z

377

Vacancy Ordering in -Fe2O3: Synchrotron X-ray Powder Diffraction and High-Resolution Electron Microscopy Studies  

Science Journals Connector (OSTI)

The structure refinement and estimation of various models of vacancy ordering in -Fe2O3 were performed. Attention is paid to the superstructure orientation with respect to well developed planes of microcrystals that depend on the precursor.

Shmakov, A.N.

1995-04-01T23:59:59.000Z

378

Fabrication and properties of ZrCZrB2/Ni cermet coatings on a magnesium alloy by atmospheric plasma spraying of SHS powders  

Science Journals Connector (OSTI)

Abstract ZrB2ZrC/Ni composite powders were successfully produced from a NiZrB4C system by self-propagating high-temperature synthesis (SHS), and ZrB2ZrC/Ni cermet coatings were deposited on a magnesium alloy substrate by atmospheric plasma spraying (APS) using the SHS-derived powders as feedstock powders. Microstructure and phase composition of the SHS powders and APS coatings were investigated by scanning electron microscopy and X-ray diffraction, respectively. Microhardness and wear resistance of the coatings were examined by using a Vickers hardness tester and pin-on-desk tribometer. The coatings exhibited lamellar and porous structure, mainly consisting of ZrB2, ZrC and Ni in addition to the by-product ZrO2. The coatings bonded well to the substrate with the bonding strength as high as 16.27MPa. Microhardness and wear resistance of the substrate were significantly improved by the coatings. The wear resistance of the coatings for the substrate initially increased and subsequently decreased with the increase in Ni content. The coating with 30wt% Ni in the feedstock powder displayed the highest microhardness of 525.0296.08 HV0.1 and the best wear resistance for the substrate.

Jiaying Xu; Binglin Zou; Sumei Zhao; Yu Hui; Wenzhi Huang; Xin Zhou; Ying Wang; Xiaolong Cai; Xueqiang Cao

2014-01-01T23:59:59.000Z

379

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE  

E-Print Network (OSTI)

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE VESSELS Y. S. Choi1 '3 , M. N), powder insulation, and foam insulation, are used in the cryogenic storage vessels. Among CP823, Advances in Cjyogenie Engineering: Transactions of the Cryogenic Engineering Conference - CEC, Vol. 51, edited by J. G

Chang, Ho-Myung

380

Sinterable powders from laser driven reactions : final report  

E-Print Network (OSTI)

Extremely fine, uniform ceramic powders have been synthesized from Sil4 NH3 and C2H4 gas phase reactants that are heated by absorbing optical energy emitted from a C02 laser. Resulting Si, Si3N4 and SiC powders have been ...

Haggerty, John Scarseth

1981-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Publications from Research Conducted at SNAP | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Publications from Research Conducted at SNAP Publications from Research Conducted at SNAP 2013 Publications Boehler R., Guthrie M., Molaison J.J., dos Santos A. M., Sinogeikin S., Machida S., Pradhan N., Tulk C. A., "Large-volume diamond cells for neutron diffraction above 90 GPa", High Pressure Research 33, 546-554 (2013). Guthrie M., Boehler R., Tulk C. A., Molaison J. J., dos Santos A. M., Li K., Hemley R. J., "Neutron diffraction observations of interstitial protons in dense ice", Proceedings of the National Academy of Sciences of the USA 110, 10552-10556 (2013). Hirai S., dos Santos A. M., Shapiro M. C., Molaison J. J., Pradhan N., Guthrie M., Tulk C. A., Fisher I. R., Mao W. L., "Giant atomic displacement at a magnetic phase transition in metastable Mn3O4", Physical

382

Solution Synthesis and Processing of PZT Materials for Neutron Generator Applications  

SciTech Connect

A new solution synthesis route has been developed for the preparation of lead-based ferroelectric materials (patent filed). The process produces controlled stoichiometry precursor powders by non-aqueous precipitation. For a given ferroelectric material to be prepared, a metal acetate/alkoxide solution containing constituent metal species in the appropriate ratio is mixed with an oxalic acid/n-propanol precipitant solution. An oxalate coprecipitate is instantly fonned upon mixing that quantitatively removes the metals from solution. Most of the process development was focused on the synthesis and processing of niobium-substituted lead zirconate titanate with a Zr-to-Ti ratio of 95:5 (PNZT 95/5) that has an application in neutron generator power supplies. The process was scaled to produce 1.6 kg of the PNZT 95/5 powder using either a sen-ii-batch or a continuous precipitation scheme. Several of the PNZT 95/5 powder lots were processed into ceramic slug form. The slugs in turn were processed into components and characterized. The physical properties and electrical performance (including explosive functional testing of the components met the requirements set for the neutron generator application. Also, it has been demonstrated that the process is highly reproducible with respect to the properties of the powders it produces and the properties of the ceramics prepared from its powders. The work described in this report was funded by Sandia's Laboratory Directed Research and Development Program.

Anderson, M.A.; Ewsuk, K.G.; Montoya, T.V.; Moore, R.H.; Sipola, D.L.; Tuttle, B.A.; Voigt, J.A.

1998-12-01T23:59:59.000Z

383

Neutron structural characterization and transport properties of oxidized and reduced La0.5Sr0.5M0.5Ti0.5O3 (M?=?Mn, Fe) perovskites: Possible electrode materials in solid-oxide fuel cells  

Science Journals Connector (OSTI)

Oxygen-stoichiometric La0.5Sr0.5M0.5Ti0.5O3 (M?=?Mn Fe) perovskites and the corresponding reduced specimens of La0.5Sr0.5M0.5Ti0.5O3-? composition have been prepared and characterized by x-ray diffraction and neutron powder diffraction (NPD) in complement with thermal analysis electrical conductivity and thermal expansion measurements. NPD data show that these perovskites are all orthorhombic space group Pbnm (No. 62). The total reduction of M3+ to M2+ in the reduced phases is accompanied with the occurrence of oxygen vacancies which was confirmed by thermogravimetric analysis (TGA). Above room-temperature these phases undergo two structural phase transitions studied in situ from NPD data; the former to a tetragonal (I4/mcm) structure and the second one to a cubic (Pm-3m) phase. All the oxides display a semiconductor-like behavior with a maximum conductivity value of 15?Scm?1 for the oxidized La0.5Sr0.5Mn0.5Ti0.5O3 phase at 850?C. The measured thermal expansion coefficients perfectly match with the values usually displayed by solid-oxide fuel cell (SOFC) electrolytes. The obtained results present these perovskites as alternative electrodes for SOFCs.

J. A. Alonso; D. Perez-Coll; M. T. Fernndez-Daz

2013-01-01T23:59:59.000Z

384

Cold neutron research facility at the Budapest Neutron Centre  

Science Journals Connector (OSTI)

The new cold neutron research facility has been routinely operated at the Budapest Neutron Centre (BNC) since February 2001. This ... of equipment consists of a liquid hydrogen cold neutron source, an optimised s...

L. Rosta

2002-12-01T23:59:59.000Z

385

Measurement of Thermal Neutron Flux in Photo-Neutron Source  

Science Journals Connector (OSTI)

The Photo-Neutron Source (PNS) project is a study ... design, simulation and construction an accelerator based neutron source for Boron Neutron Capture Therapy (BNCT). The system uses ... medical linear accelerat...

A. Taheri; A. Torkamani; A. Pazirandeh

2013-01-01T23:59:59.000Z

386

Neutron sources and applications  

SciTech Connect

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.

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

1994-01-01T23:59:59.000Z

387

Spallation Neutron Source  

NLE Websites -- All DOE Office Websites (Extended Search)

D/gim D/gim Spallation Neutron Source SNS is an accelerator-based neutron source. This one-of-a-kind facility pro- vides the most intense pulsed neutron beams in the world. When ramped up to its full beam power of 1.4 MW, SNS will be eight times more powerful than today's best facility. It will give researchers more detailed snapshots of the smallest samples of physical and biological materials than ever before

388

Industry - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Industry banner Industry banner Neutron scattering research has applications in practically every field, and neutron research at ORNL is leading to productive partnerships with the industrial and business communities. We welcome proposals for all types of research, including those involving proprietary work. Recent studies have led to discoveries with potential applications in fields such as medicine, energy, and various metals technologies. For more information, please see our recent research highlights. Research Collaborations Industry-Driven Research Benefits Plastics Manufacturing Corning uses VULCAN to test limits of ceramic material for car emission controls, filtration devices Neutrons Probe Inner Workings of Batteries Industry and Neutron Science: Working To Make a Match

389

Neutron wave packet tomography  

E-Print Network (OSTI)

A tomographic technique is introduced in order to determine the quantum state of the center of mass motion of neutrons. An experiment is proposed and numerically analyzed.

G. Badurek; P. Facchi; Y. Hasegawa; Z. Hradil; S. Pascazio; H. Rauch; J. Rehacek; T. Yoneda

2005-03-29T23:59:59.000Z

390

Neutron Science Forum | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

environment for discussion, innovation, and dissemination of information within the neutron scattering community as well as engaging closely related disciplines through...

391

Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

User Office User Program Manager Laura Morris Edwards 865.574.2966 ORNL study uses neutron scattering, supercomputing to demystify forces at play in biofuel production Full...

392

Polarizability of the Neutron  

Science Journals Connector (OSTI)

Experiments on scattering of low-energy neutrons by heavy elements may give information concerning the electric polarizability of the neutron. The relation of the electric polarizability to the low-energy neutron scattering data is developed. One pertinent experiment is discussed and from this an upper bound on the polarizability is obtained. This upper bound to the polarizability ? is an order of magnitude larger than the meson-theoretic estimate of ?. If the value of ? is as small as is predicted by meson theory, or by an analysis of the pion photoproduction data, then it is unlikely to be observed in neutron scattering experiments of the presently achievable accuracy.

R. M. Thaler

1959-05-01T23:59:59.000Z

393

Diffractive Higgs boson photoproduction in $?p$ process  

E-Print Network (OSTI)

We explore an alternative process for the diffractive Higgs boson production in peripheral pp collisions arising from Double Pomeron Exchange in photon-proton interaction. We introduce the impact factor formalism in order to enable the gluon ladder exchange in the photon-proton subprocess, and to permit the central Higgs production. The event rate for the diffractive Higgs production in central rapidity is estimated to be about 0.6 pb at Tevatron and LHC energies. This result is higher than predictions from other approaches for diffractive Higgs production, showing that the alternative production process leads to an enhanced signal for the detection of the Higgs boson at hadron colliders. Our results are compared to those obtained from a similar approach proposed by the Durham group. In this way we may examine the future developments in its application to pp and AA collisions.

M. B. Gay Ducati; G. G. Silveira

2008-12-05T23:59:59.000Z

394

Ultra-high density diffraction grating  

SciTech Connect

A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.

Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.

2012-12-11T23:59:59.000Z

395

Neutron superfluidity and unusual nuclear shapes in neutron stars crusts  

Science Journals Connector (OSTI)

We calculate in the frame-work of a semiclassical model the neutron superfluidity in the crust of neutron stars, accounting for the presence of unusual....

G. Lazzari; F. V. De Blasio

1994-01-01T23:59:59.000Z

396

Neutron capture cross sections for neutron-rich isotopes  

Science Journals Connector (OSTI)

Average continuum (Hauser-Feshbach) and resonance (Breit-Wigner) neutron capture rates for neutron-rich isotopes, determined on the basis of...

B. Leist; W. Ziegert; M. Wiescher

1985-01-01T23:59:59.000Z

397

Neutron and Nuclear Science News  

NLE Websites -- All DOE Office Websites (Extended Search)

News Recent news and events related to neutron and nuclear science at LANSCE. Neutron and Nuclear Science News Links Neutron and Nuclear Science News Media Links Profiles Events at...

398

Neutron Scattering Methods in Chemistry  

Science Journals Connector (OSTI)

Starting with basic properties of the neutron, this chapter reviews the most important neutron scattering methods that provide valuable information for a ... wide, from standard methods of crystallography to neutron

L. Pusztai

2011-01-01T23:59:59.000Z

399

Odd CP contributions to diffractive processes  

Science Journals Connector (OSTI)

We investigate contributions to diffractive scattering, which are odd under C and P parity. Comparison of p-p and p-p scattering indicates that these odderon contributions are very small and we show how a diquark clustering in the proton can explain this effect. A good probe for the odderon exchange is the photo- and electroproduction of pseudoscalar mesons. We concentrate on the ?0 and show that the quasielastic ?0 production is again strongly suppressed for a diquark structure of the proton whereas the cross sections for diffractive proton dissociation are larger by orders of magnitude and rather independent of the proton structure.

Michael Rueter; H. G. Dosch; O. Nachtmann

1998-11-30T23:59:59.000Z

400

Diffraction at the Tevatron and the LHC  

E-Print Network (OSTI)

In these lectures, we present and discuss the most recent results on inclusive diffraction at the Tevatron collider and give the prospects at the LHC. We also describe the search for exclusive events at the Tevatron. Of special interest is the exclusive production of Higgs boson and heavy objects ($W$, top, stop pairs) at the LHC which will require precise measurements and analyses of inclusive and exclusive diffraction to constrain further the gluon density in the pomeron. At the end of these lectures, we describe the projects to install forward detectors at the LHC to fulfil these measurements.

C. Royon

2008-05-02T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

A TIME-OF-FLIGHT SPECTROMETER FOR ELASTIC NEUTRON SCATTERING ON POWDERED SAMPLES  

E-Print Network (OSTI)

on test samples with simple structure (UO2 give a reliability factor R of 1.3 % which com- pares fairly of the Melusine 8 MW light-water reactor of the Centre d'Etudes Nucléaires de Grenoble. The thermal flux pattern, a matrix formalism has been deve- loped [6,] [7], [8], allowing the analysis of a real

Paris-Sud XI, Université de

402

Device for Writing the Time Tail from Spallation Neutron Pulses  

SciTech Connect

Recent work at Los Alamos Neutron Science Center (LANSCE), has shown that there are large gains in neutron beam intensity to be made by using coupled moderators at spallation neutron sources. Most of these gains result from broadening the pulse-width in time. However the accompanying longer exponential tail at large emission times can be a problem in that it introduces relatively large beam-related backgrounds at high resolutions. We have designed a device that can reshape the moderated neutron beam by cutting the time-tail so that a sharp time resolution can be re-established without a significant loss in intensity. In this work the basic principles behind the tail-cutter and some initial results of Monte Carlo simulations are described. Unwanted neutrons in the long time-tail are diffracted out of the transmitted neutron beam by a nested stack of aperiodic multi-layers, rocking at the same frequency as the source. Nested aperiodic multi-layers have recently been used at X-ray sources and as band-pass filters in quasi-Laue neutron experiments at reactor neutron sources. Optical devices that rock in synchronization with a pulsed neutron beam are relatively new but are already under construction at LANSCE. The tail-cutter described here is a novel concept that uses existing multi-layer technology in a new way for spallation neutrons. Coupled moderators in combination with beam shaping devices offer the means of increasing flux whilst maintaining a sharp time distribution. A prototype device is being constructed for the protein crystallography station at LANSCE. The protein crystallography station incorporates a water moderator that has been judiciously coupled in order to increase the flux over neutron energies that are important to structural biology (3-80meV). This development in moderator design is particularly important because protein crystallography is flux limited and because conventional ambient water and cold hydrogen moderators do not provide relatively large neutron fluxes over this neutron energy range.

Langan, P. (Paul); Schoenborn, Benno P.; Langan, P. (Paul); Schoenborn, Benno P.; Daemen, L. L. (Luc L.)

2001-01-01T23:59:59.000Z

403

Neutron activation experiments in radiochemistry  

Science Journals Connector (OSTI)

Neutron activation experiments in radiochemistry ... Describes experimentation involving the neutron activation of a variety of samples irradiated in a subcritical reactor and a paraffin-moderated source. ...

Karl S. Vorres

1960-01-01T23:59:59.000Z

404

Neutron Stars and Fractal Dimensionality  

E-Print Network (OSTI)

We argue that the material inside Neutron stars behaves anomalously with fractal statistics and that in principle, we could induce mini Neutron stars, with the release of energy.

Burra G. Sidharth

2008-05-06T23:59:59.000Z

405

A history of the neutron  

Science Journals Connector (OSTI)

A history of the neutron ... Describes some of the individuals and the work they did leading to the discovery of the neutron. ...

Vasilis Lavrakas

1952-01-01T23:59:59.000Z

406

Neutron and Nuclear Science Publications  

NLE Websites -- All DOE Office Websites (Extended Search)

Publications Recent publications related to neutron and nuclear science at LANSCE. Neutron and Nuclear Science Publications Chi-Nu Publications DANCE Publications GEANIE...

407

Neutron and Nuclear Science News  

NLE Websites -- All DOE Office Websites (Extended Search)

News Recent news and events related to neutron and nuclear science at LANSCE. Neutron and Nuclear Science News Nuclear science observations and opportunities at the Los Alamos...

408

Neutron Science Research Areas | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Home | Science & Discovery | Neutron Science | Research Areas SHARE Research Areas Neutron scattering research at ORNL covers four broad research areas: biology and soft...

409

LANSCE School on Neutron Scattering:  

NLE Websites -- All DOE Office Websites (Extended Search)

11 th LANSCE School on Neutron Scattering: Materials at the Mesoscale Lujan Center Los Alamos Neutron Science Center Los Alamos National Laboratory lansce.lanl.govneutronschool...

410

Advances in specular neutron reflectometry  

Science Journals Connector (OSTI)

Specular neutron reflectometry provides a depth profile of the scattering ... material. To date, numerous productive applications of neutron reflectometry have been demonstrated. With the new development ... stil...

C.F. Majkrzak; N.F. Berk

2002-12-01T23:59:59.000Z

411

E-Print Network 3.0 - aluminum powder mixtures Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

4210: Manufacturing Processes and Engineering Summary: .S. Colton GIT 2009 17 12;Compacting Pressures for Various Metal Powders P Metal Pressure (MPa) Aluminum... Metal Powder...

412

Category:Neutron Log | Open Energy Information  

Open Energy Info (EERE)

Neutron Log page? For detailed information on Neutron Log, click here. Category:Neutron Log Add.png Add a new Neutron Log Technique Pages in category "Neutron Log" This category...

413

Chemical & EngChemical/Engineering Materials Division | Neutron Science |  

NLE Websites -- All DOE Office Websites (Extended Search)

Chemical and Engineering Materials Division Chemical and Engineering Materials Division SHARE Chemical and Engineering Materials Division CEMD Director Mike Simonson The Chemical and Engineering Materials Division (CEMD) supports neutron-based research at SNS and HFIR in understanding the structure and dynamics of chemical systems and novel engineering materials. The user community takes advantage of division-supported capabilities of neutron scattering for measurements over wide ranges of experimental and operating conditions, including studies of chemical and physical changes in situ. User experiments with diffraction, small-angle scattering, inelastic and quasielastic scattering, and neutron imaging instruments address a range of problems in chemistry and in engineering materials research. Current areas of research supported by the division include the structure

414

Neutron Capture Therapy  

Science Journals Connector (OSTI)

... . Only those elements which have a high thermal-neutron capture cross-section, such as boron-10, lithium-6, and uranium-235, are useful. This suggestion was first put forward ... was first put forward in 1936 by Locher. The utilization of thermal neutron capture by boron-10 for the treatment of human-brain tumours, chiefly glioblastoma multiforme, has been under investigation ...

1961-09-23T23:59:59.000Z

415

Neutron capture therapies  

DOE Patents (OSTI)

In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

Yanch, Jacquelyn C. (Cambridge, MA); Shefer, Ruth E. (Newton, MA); Klinkowstein, Robert E. (Winchester, MA)

1999-01-01T23:59:59.000Z

416

Neutron calibration facilities  

Science Journals Connector (OSTI)

......shut down. A recent development for a thermal neutron calibration field is a neutron guide used at the research reactor GKSS Geesthacht(35). The result is a high-intensity thermal beam providing a flux of up to 106 s1 with a field size of about 2.5 2......

H. Schuhmacher

2004-08-01T23:59:59.000Z

417

A computational inverse diffraction grating problem  

E-Print Network (OSTI)

Mar 2, 2012 ... od and a variational (finite element) method have been developed in [3,4]. ... problems in diffractive optics, which is to design a grating structure that .... where the free-space quasiperiodic Green function is given ex- plicitly as.

2012-02-29T23:59:59.000Z

418

DIFFRACTION STUDIES OF ICE Alexe BOSAK  

E-Print Network (OSTI)

Ic 28o halo observed at least 7 times since 1629 octahedral particles of ice Ic! #12;Cooling downDIFFRACTION STUDIES OF ICE Alexeï BOSAK European Synchrotron Radiation Facility #12;Ice as the mild threat ice Ih the only ice in the crust #12;Ice as the absolute weapon Ice IX : melting point 45.8°C

Titov, Anatoly

419

Estimating nanoparticle size from diffraction measurements  

Science Journals Connector (OSTI)

A Fourier transform of a Debye-Scherrer diffraction pattern can be used to estimate the characteristic size of nanoparticle samples. This method is insensitive to nanoparticle structure and therefore preferable to the Scherrer formula (which is unreliable because it assumes an underlying size-limited perfect crystal structure).

Hall, B.D.

2000-12-01T23:59:59.000Z

420

Near-field diffractive elements Daniel Marks  

E-Print Network (OSTI)

by a near-field diffractive element (NDE) that scatters the high-spatial-frequency components of the field susceptibility r , and the NDE is described by the susceptibilty r . The field obeys the equation 2 U r +k0 2 U r to first order in both the NDE and the sample susceptibilities. It is assumed that the background terms

Bhargava, Rohit

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Diffraction at HERA, Tevatron and LHC  

E-Print Network (OSTI)

In this short review, we describe some of the results on diffraction from the Tevatron and give some prospects for the LHC. In particular, we discuss the search for exclusive events at the Tevatron and their importance for the LHC program/ We finish by presenting the project of installing forward detectors in the ATLAS collaboration at 220 and 420 m.

C. Royon

2009-04-14T23:59:59.000Z

422

Neutron Scattering Software  

NLE Websites -- All DOE Office Websites (Extended Search)

Software Software A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for archival purposes but no new content will be added. We encourage everyone interested in neutron scattering to take full advantage of this exciting new resource for our community. Neutronsources.org Data Formats NeXus: Neutron and X-ray Data Format Crystallographic Binary Format (CBF/imgCIF) Hierarchical Data Format (HDF) Data Analysis and Visualization Data Analysis for Neutron Scattering Experiments (DANSE): distributed data analysis project Large Array Manipulation Program (LAMP): IDL-based data analysis and visualization

423

Industry - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Industry and Neutron Science Industry and Neutron Science Industry and Neutron Science: Working To Make a Match "In fundamental research, we want to know everything. Industry wants to know enough to answer a question." Research Contact: Mike Crawford September 2011, Written by Deborah Counce Mike Crawford and Souleymane Diallo Mike Crawford of Dupont (right) and Souleymane Diallo, instrument scientist for the Backscattering Spectrometer at SNS, prepare a material sample for an experiment on the instrument. Industrial users are starting to eye the potential of neutron science for solving problems that can't be solved in any other way. At the same time, the SNS and HFIR neutron science facilities at ORNL are exploring ways to woo such users and to make a match of it, to the benefit of both.

424

Pocked surface neutron detector  

DOE Patents (OSTI)

The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

2003-04-08T23:59:59.000Z

425

Structure of the Neutron  

Science Journals Connector (OSTI)

In an earlier paper, the contribution of the meson current to the electromagnetic structure of the nucleon was calculated by use of the dispersion relations for pion-nucleon scattering. Here the contribution of the nucleon current to the electromagnetic structure of the neutron is obtained analogously by use of the dispersion relations for neutron-proton scattering. Only the contribution from the one-pion and two-pion states of nucleon-nucleon scattering is considered. It is found that both states reduce the neutron-electron potential, i.e., leads to a smaller charge radius of the neutron. The contribution from the deuteron state is shown to be negligible. The resulting mean-square radii of the neutron, including the contributions of both meson and nucleon current, are (0.2310-13cm)2 for the charge distribution and (0.4110-13cm)2 for the magnetic moment distribution with f2=0.08.

Katsumi Tanaka

1959-01-15T23:59:59.000Z

426

THERMAL NEUTRON BACKSCATTER IMAGING.  

SciTech Connect

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

2004-10-16T23:59:59.000Z

427

Instrument and method for focusing x rays, gamma rays, and neutrons  

DOE Patents (OSTI)

A crystal-diffraction instrument or diffraction-grating instrument is described with an improved crystalline structure or grating spacing structure having a face for receiving a beam of photons or neutrons and diffraction planar spacing or grating spacing along that face with the spacing increasing progressively along the face to provide a decreasing Bragg diffraction angle for a monochromatic radiation and thereby increasing the usable area and acceptance angle. The increased planar spacing for the diffraction crystal is provided by the use of a temperature differential across the line structures with different compositions, by an individual crystalline structure with a varying composition and thereby a changing planar spacing along its face, and by combinations of these techniques. The increased diffraction grating element spacing is generated during the fabrication of the diffraction grating by controlling the cutting tool that is cutting the grooves or controlling the laser beam, electron beam, or ion beam that is exposing the resist layer, etc. It is also possible to vary this variation in grating spacing by applying a thermal gradient to the diffraction grating in much the same manner as is done in the crystal-diffraction case.

Smither, R.K.

1982-03-25T23:59:59.000Z

428

Instrument and method for focusing X-rays, gamma rays and neutrons  

DOE Patents (OSTI)

A crystal diffraction instrument or diffraction grating instrument with an improved crystalline structure or grating spacing structure having a face for receiving a beam of photons or neutrons and diffraction planar spacing or grating spacing along that face with the spacing increasing progressively along the face to provide a decreasing Bragg diffraction angle for a monochromatic radiation and thereby increasing the usable area and acceptance angle. The increased planar spacing for the diffraction crystal is provided by the use of a temperature differential across the crystalline structure, by assembling a plurality of crystalline structures with different compositions, by an individual crystalline structure with a varying composition and thereby a changing planar spacing along its face, and by combinations of these techniques. The increased diffraction grating element spacing is generated during the fabrication of the diffraction grating by controlling the cutting tool that is cutting the grooves or controlling the laser beam, electron beam or ion beam that is exposing the resist layer, etc. It is also possible to vary this variation in grating spacing by applying a thermal gradient to the diffraction grating in much the same manner as is done in the crystal diffraction case.

Smither, Robert K. (Hinsdale, IL)

1984-01-01T23:59:59.000Z

429

Solid phases of spatially nanoconfined oxygen: A neutron scattering study  

SciTech Connect

We present a comprehensive neutron scattering study on solid oxygen spatially confined in 12 nm wide alumina nanochannels. Elastic scattering experiments reveal a structural phase sequence known from bulk oxygen. With decreasing temperature cubic ?-, orthorhombic ?- and monoclinic ?-phases are unambiguously identified in confinement. Weak antiferromagnetic ordering is observed in the confined monoclinic ?-phase. Rocking scans reveal that oxygen nanocrystals inside the tubular channels do not form an isotropic powder. Rather, they exhibit preferred orientations depending on thermal history and the very mechanisms, which guide the structural transitions.

Kojda, Danny [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany) [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany); Freie Universitt Berlin, 14195 Berlin (Germany); Wallacher, Dirk; Hofmann, Tommy, E-mail: tommy.hofmann@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany)] [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany); Baudoin, Simon; Hansen, Thomas [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)] [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Huber, Patrick [Technische Universitt Hamburg-Harburg, 21073 Hamburg (Germany)] [Technische Universitt Hamburg-Harburg, 21073 Hamburg (Germany)

2014-01-14T23:59:59.000Z

430

Neutron Bragg-edge-imaging for strain mapping under in situ tensile loading  

SciTech Connect

Wavelength selective neutron radiography at a cold neutron reactor source was used to measure strain and determine (residual) stresses in a steel sample under plane stress conditions. We present a new technique that uses an energy-resolved neutron imaging system based on a double crystal monochromator and is equipped with a specially developed (in situ) biaxial load frame to perform Bragg edge based transmission imaging. The neutron imaging technique provides a viewing area of 7 cm by 7 cm with a spatial resolution on the order of {approx} 100 {mu}m. The stress-induced shifts of the Bragg edge corresponding to the (110) lattice plane were resolved spatially for a ferritic steel alloy A36 (ASTM international) sample. Furthermore it is demonstrated that results agree with comparative data obtained using neutron diffraction and resistance based strain-gauge rosettes.

Woracek, R. [University of Tennessee, CEE Department, 223 Perkins Hall, Knoxville, Tennessee 37996 (United States); Helmholtz Zentrum Berlin, Hahn Meitner Platz 1, D-14109 Berlin (Germany); Penumadu, D. [University of Tennessee, CEE Department, 223 Perkins Hall, Knoxville, Tennessee 37996 (United States); Kardjilov, N.; Hilger, A.; Strobl, M.; Wimpory, R. C.; Manke, I.; Banhart, J. [Helmholtz Zentrum Berlin, Hahn Meitner Platz 1, D-14109 Berlin (Germany)

2011-05-01T23:59:59.000Z

431

Environmentally stable reactive alloy powders and method of making same  

DOE Patents (OSTI)

Apparatus and method are disclosed for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloys needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment. 7 figs.

Anderson, I.E.; Lograsso, B.K.; Terpstra, R.L.

1998-09-22T23:59:59.000Z

432

Process for synthesizing compounds from elemental powders and product  

DOE Patents (OSTI)

A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

Rabin, B.H.; Wright, R.N.

1993-12-14T23:59:59.000Z

433

Consolidation of aluminum 6061 powder by equal channel angular extrusion  

E-Print Network (OSTI)

, the powder is placed in a deformable mold ? often rubber, glass, or stainless steel. The container is evacuated and welded shut and then placed inside the HIP unit. A high- pressure gas or liquid surrounds the powder mold and applies pressure equally on all... oxide films and provide new surface area for welding. Next, the particles are resistance heated and pressure is applied for about 15 minutes. Applied temperatures are lower than HIP temperatures, and PAS uses much shorter consolidation times ? minutes...

Pearson, John Montgomery

1997-01-01T23:59:59.000Z

434

Laser:powder:substrate interactions in laser cladding and casting  

Science Journals Connector (OSTI)

Laser cladding and the recently developed laser casting technique are similar in their physical mechanisms. A transition from cladding to casting and vice versa can be achieved by proper control of the process parameters, both for preplaced and blown powder. In the present work, the preplaced powder technique is studied at a fundamental level. Its physical nature is responsible for a large operating window of dilution free cladding on the one hand and bond free casting on the other.

A.F.H. Kaplan; John Powell; Hans Gedda

2010-01-01T23:59:59.000Z

435

Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids  

SciTech Connect

Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.

B. Olinger

2005-04-15T23:59:59.000Z

436

Titanium Metal Powder Production by the Plasma Quench Process  

SciTech Connect

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

R. A. Cordes; A. Donaldson

2000-09-01T23:59:59.000Z

437

An investigation on the influence of milling time and calcination temperature on the characterization of nano cerium oxide powder synthesized by mechanochemical route  

SciTech Connect

Highlights: ? Synthesis of nanosized CeO{sub 2} was carried out using mechanochemical reactions plus sequential calcinations procedure. ? The effect of milling time and calcinations procedure on crystallite size and surface area of the as-synthesized powders was investigated. ? The extended milling times were exposed to result in the smaller crystallite size, and hence higher surface area for the as-synthesized powder. ? Higher calcinations temperatures, on the other hand, led to the as-synthesized powder with a larger crystallite size and therefore, lower surface area. ? Activation energy for nanocrystallite growth was calculated during the calcinations procedure and the aforementioned crystallite growth was found to be conducted in the light of interfacial reactions. -- Abstract: The synthesis of nano-sized CeO{sub 2} powder was investigated via mechanochemical reactions between hydrate cerium chloride and sodium hydroxide as the starting materials. The process was followed by a subsequent calcination procedure. Characterization of as-synthesized powder was performed using X-ray diffraction, FTIR spectroscopy, BrunnerEmmettTeller (BET) nitrogen gas absorption, scanning electron microscopy (SEM) and particle size analyzer (PSA). The precursors were milled for different milling times and then were subjected to different heat treatment procedure at variable temperatures from 100 to 700 C. According to the results, milling time and calcination temperatures induce paramountal effects on crystallite size and surface area of as-synthesized powders. In addition, the average activation energy for the growth of nanocrystals during calcination was determined to be about 12.53 kJ/mol, suggesting the influence of interfacial reactions on the crystallite growth during the calcination procedure.

Aminzare, M., E-mail: masoudaminzare@yahoo.com [Materials Engineering Department, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Amoozegar, Z. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of)] [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Sadrnezhaad, S.K. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)] [Department of Materials Science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2012-11-15T23:59:59.000Z

438

X-ray Diffraction (XRD) 1.0 What is X-ray Diffraction  

E-Print Network (OSTI)

X-ray Diffraction (XRD) · 1.0 What is X-ray Diffraction · 2.0 Basics of Crystallography · 3.0 Production of X-rays · 4.0 Applications of XRD · 5.0 Instrumental Sources of Error · 6.0 Conclusions #12 why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta

Moeck, Peter

439

Neutron LifetimeNeutron Lifetime IUCF Colloquium April 13,  

E-Print Network (OSTI)

Neutron LifetimeNeutron Lifetime IUCF Colloquium April 13, 2007 Albert Steyerl Department 940 878.5±0.8 885.7±0.8 new result neutronlifetime(),s year world average Neutron lifetime data #12 world average Neutron lifetime data A. Serebrov et al. 2005Storage of ultra-cold neutrons878.5 ±±±± 0

Steyerl, Albert

440

Hyperons in neutron stars  

E-Print Network (OSTI)

Using the Dirac-Brueckner-Hartree-Fock approach, the properties of neutron-star matter including hyperons are investigated. In the calculation, we consider both time and space components of the vector self-energies of baryons as well as the scalar ones. Furthermore, the effect of negative-energy states of baryons is partly taken into account. We obtain the maximum neutron-star mass of $2.08\\,M_{\\odot}$, which is consistent with the recently observed, massive neutron stars. We discuss a universal, repulsive three-body force for hyperons in matter.

Katayama, Tetsuya

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Phase-shifting point diffraction interferometer  

DOE Patents (OSTI)

Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams. 8 figs.

Medecki, H.

1998-11-10T23:59:59.000Z

442

QCD and Hard Diffraction at the LHC  

E-Print Network (OSTI)

As an introduction to QCD at the LHC I give an overview of QCD at the Tevatron, emphasizing the high Q^2 frontier which will be taken over by the LHC. After describing briefly the LHC detectors I discuss high mass diffraction, in particular central exclusive production of Higgs and vector boson pairs. I introduce the FP420 project to measure the scattered protons 420m downstream of ATLAS and CMS.

Michael G. Albrow

2005-09-26T23:59:59.000Z

443

Industry - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

PartTec PartTec ORNL, PartTec Inc. Licensing Agreement ORNL and PartTec sign licensing agreement (Front) ORNL Deputy Director for Science & Technology Thomas Zacharia and PartTec CEO Herschel Workman. (Back) Bruce Hannan (SNS), PartTec production manager Craig Kline, Rick Riedel (SNS), Jason Hodges (SNS) and Ron Cooper (SNS). The SNS guys were on the development team. Representatives from Oak Ridge National Laboratory and PartTec, an Indiana-based firm, formally signed a licensing agreement Thursday, Aug. 12, to market an advanced neutron detector system developed for the Spallation Neutron Source. The Shifting Scintillator Neutron Detector can determine the time and position of captured neutrons, which enables researchers to obtain very accurate time-of-flight measurements.

444

Education | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Education banner Education banner Sunil Sinha A Chat with Sunil Sinha, Distinguished Professor of Physics at the University of California-San Diego and speaker at the recent CNMS-SNS Research Forum more... The purpose of the Spallation Neutron Source and the High Flux Isotope Reactor is to facilitate neutron scattering as an integral tool for scientific research and technological development across many scientific and engineering domains within the scientific, academic,and industrial communities. Coupled with this role is a recognized need to inspire, educate, and facilitate the next generation of users and hence foster enhanced use of the unique neutron scattering facilities at ORNL. This is the central theme of the education activities within the Neutron Sciences Directorate (NScD).

445

ORNL Neutron Sciences Instruments  

NLE Websites -- All DOE Office Websites (Extended Search)

Instruments banner Instruments banner ORNL Neutron Sciences Instruments SNS and HFIR provide researchers with two complementary world-class suites of neutron scattering instruments and beam lines. All the instruments are supported by a variety of sample environments and data analysis and visualization capabilities. Before submitting a proposal for a specific instrument, please contact the appropriate instrument scientist to make sure your research is feasible for that instrument. Instruments Currently Available to Users SNS Beam Line Instrument Name HFIR Beam Line Instrument Name 1B NOMAD Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS Backscattering Spectrometer CG-1D IMAGING Neutron Imaging Prototype Facility 3 SNAP Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS

446

Neutron Science Center  

NLE Websites -- All DOE Office Websites (Extended Search)

to have rare opportunity to tour Neutron Science Center May 10, 2011 LANL Rosenfest will celebrate life of LANSCE founder Louis Rosen and offer tour LOS ALAMOS, New Mexico, May 10,...

447

Shifting scintillator neutron detector  

DOE Patents (OSTI)

Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

2014-03-04T23:59:59.000Z

448

Scattering of Slow Neutrons  

Science Journals Connector (OSTI)

1 September 1937 research-article Scattering of Slow Neutrons M. Goldhaber G. H. Briggs The Royal Society is collaborating with JSTOR to digitize, preserve, and extend access to Proceedings...

1937-01-01T23:59:59.000Z

449

Neutron stars - thermal emitters  

E-Print Network (OSTI)

Confronting theoretical models with observations of thermal radiation emitted by neutron stars is one of the most important ways to understand the properties of both, superdense matter in the interiors of the neutron stars and dense magnetized plasmas in their outer layers. Here we review the theory of thermal emission from the surface layers of strongly magnetized neutron stars, and the main properties of the observational data. In particular, we focus on the nearby sources for which a clear thermal component has been detected, without being contaminated by other emission processes (magnetosphere, accretion, nebulae). We also discuss the applications of the modern theoretical models of the formation of spectra of strongly magnetized neutron stars to the observed thermally emitting objects.

Potekhin, A Y; Pons, J A

2014-01-01T23:59:59.000Z

450

Direct laser powder deposition - 'State of the Art'  

SciTech Connect

Recent developments on Laser Cladding and Rapid Prototyping have led to Solid Freeform Fabrication (SFF) technologies that produce net shape metal components by laser fusion of metal powder alloys. These processes are known by various names such as Directed Light Fabrication (DLF{trademark}), Laser Engineered Net Shaping (LENS{trademark}), and Direct Metal Deposition (DMD{trademark}) to name a few. These types of processes can be referred to as direct laser powder deposition (DLPD). DLPD involves fusing metal alloy powders in the focal point of a laser (or lasers) that is (are) being controlled by Computer Aided Design-Computer Aided Manufacturing (CAD-CAM) technology. DLPD technology has the capability to produce fully dense components with little need for subsequent processing. Research and development of DLPD is being conducted throughout the world. The list of facilities conducting work in this area continues to grow (over 25 identified in North America alone). Selective Laser Sintering (SLS{trademark}) is another type of SFF technology based on laser fusion of powder. The SLS technology was developed as a rapid prototyping technique, whereas DLPD is an extension of the laser cladding technology. Most of the effort in SLS has been directed towards plastics and ceramics. In SLS, the powder is pre-placed by rolling out a layer for each laser pass. The computer control selects where in the layer the powder will be sintered by the laser. Sequential layers are sintered similarly forming a shape. In DLPD, powder is fed directly into a molten metal pool formed at the focal point of the laser where it is melted. As the laser moves on the material it rapidly resolidifies to form a shape. This talk elaborates on the state of these developments.

Sears, J.W.

1999-11-01T23:59:59.000Z

451

Data Analysis & Visualization | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Data Analysis and Visualization SHARE Neutron Data Analysis and Visualization As the data sets generated by the increasingly powerful neutron scattering instruments at HFIR...

452

Science Education Programs | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

with Neutrons Graduate & Post-doctoral Programs Student & Teacher Programs Science Forum Neutron Scattering Tutorials Kids' Corner NScD Careers Supporting Organizations Neutron...

453

Fast Pulsing Neutron Generators for Security Application  

E-Print Network (OSTI)

FAST PULSING NEUTRON GENERATORS FOR SECURITY APPLICATION* Q.time/fast pulsing neutron generator is needed primarily forA compact neutron generator, currently being developed in

Ji, Q.

2010-01-01T23:59:59.000Z

454

Design and transformation of three dimensional pupils : diffractive and subwavelength  

E-Print Network (OSTI)

Three dimensional pupils are investigated in both diffractive and subwavelength regimes and in various applications to shape the flow of light. In diffractive regime, volume holograms are good candidates for pupils of ...

Gao, Hanhong

2014-01-01T23:59:59.000Z

455

Biological Imaging by Soft X-Ray Diffraction Microscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Biological Imaging by Soft X-Ray Diffraction Microscopy Biological Imaging by Soft X-Ray Diffraction Microscopy Print Wednesday, 30 November 2005 00:00 Electron and x-ray...

456

Leading neutron spectra  

E-Print Network (OSTI)

It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also briefly discuss the corresponding data for leading baryons produced in hadron-hadron collisions.

A. B. Kaidalov; V. A. Khoze; A. D. Martin; M. G. Ryskin

2006-02-23T23:59:59.000Z

457

Recent developments in position-sensitive neutron counting  

SciTech Connect

Continuing research on advanced methods of thermal neutron detection and position sensing with gas-filled counters was aimed at improving their performance and extending the limits of their applicability. High electron drift velocities obtained from measurements on gas mixtures containing CF/sub 4/ motivated us to evaluate the properties of /sup 3/He-CF/sub 4/ and Ar-CF/sub 4/ mixtures to show that these gases have the potential of improving the count rate capability, spatial resolution, and photon discrimination of neutron PSPCs (position-sensitive proportional counters) and fission counters. In support of the U.S. National Small-Angle Neutron Scattering (SANS) Facility we developed a large-area (65-cm x 65-cm) PSPC camera. RC position encoding was chosen for simplicity of construction, but since previous experience with this encoding method had been limited to smaller PSPCs (area < 25 cm x 25 cm), the main objective of this development was to show that RC encoding parameters and construction methods could be scaled up for larger area PSPCs. The use of the new counter gas mixtures enabled the development of position-sensitive transmission line fission counters (TLFCs) for neutron flux monitoring and a one-dimensional, curved PSPC for large-angle (130/sup 0/) neutron diffraction experiments. The main objective of these developments was to extend the capabilities of the LC-encoding method by mitigating the effects of interelectrode capacitance, and thereby increase the count rate capability.

Valentine, K.H.; Kopp, M.K.; Guerrant, G.C.; Harter, J.A.

1982-01-01T23:59:59.000Z

458

Method of collecting and processing electron diffraction data  

DOE Patents (OSTI)

A method of using electron diffraction to obtain PDFs from crystalline, nanocrystalline, and amorphous inorganic, organic, and organometallic compound.

Billinge, Simon; Farrow, Christopher; Gorelik, Tatiana E; Kanatzidis, Mercouri; Schmidt, Martin U

2014-12-30T23:59:59.000Z

459

Diffractive parton distributions: the role of the perturbative Pomeron  

E-Print Network (OSTI)

We consider the role of the perturbative Pomeron-to-parton splitting in the formation of the diffractive parton distributions.

Watt, G; Ryskin, M G

2007-01-01T23:59:59.000Z

460

Diffractive parton distributions: the role of the perturbative Pomeron  

E-Print Network (OSTI)

We consider the role of the perturbative Pomeron-to-parton splitting in the formation of the diffractive parton distributions.

G. Watt; A. D. Martin; M. G. Ryskin

2007-08-30T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

MAGNETIC NEUTRON SCATTERING  

SciTech Connect

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.

ZALIZNYAK,I.A.; LEE,S.H.

2004-07-30T23:59:59.000Z

462

Neutron Radii in Nuclei and the Neutron Equation of State  

Science Journals Connector (OSTI)

The root-mean-square radius for neutrons in nuclei is investigated in the Skyrme Hartree-Fock model. The main source of theoretical variation comes from the exchange part of the density-dependent interaction which can be related to a basic property of the neutron equation of state. A precise measurement of the neutron radius in 208Pb would place an important new constraint on the equation of state for neutron matter. The Friedman-Pandharipande neutron equation of state would lead to a very precise value of 0.160.02 fm for the difference between the neutron and the proton root-mean-square radius in 208Pb.

B. Alex Brown

2000-12-18T23:59:59.000Z

463

Charm production in diffractive DIS and PHP at ZEUS  

E-Print Network (OSTI)

The ZEUS experiment has measured charm production in diffractive DIS and in photoproduction. The data are in agreement with perturbative QCD calculations based on various parameterisations of diffractive parton distribution functions. The results are consistent with QCD factorisation in diffractive DIS and direct photoproduction.

Isabell-Alissandra Melzer-Pellmann; for the ZEUS collaboration

2007-08-03T23:59:59.000Z

464

Nanoparticle-Enhanced Diffraction Gratings for Ultrasensitive Surface Plasmon Biosensing  

E-Print Network (OSTI)

Nanoparticle-Enhanced Diffraction Gratings for Ultrasensitive Surface Plasmon Biosensing Alastair W by the adsorption of gold nanoparticles onto gold diffraction gratings. An enhanced diffraction obtained in the grating to the localized surface plasmons in the gold nanoparticles. As a first example

465

Method for producing microcomposite powders using a soap solution  

DOE Patents (OSTI)

A method for producing microcomposite powders for use in superconducting and non-superconducting applications. A particular method to produce microcomposite powders for use in superconducting applications includes the steps of: (a) preparing a solution including ammonium soap; (b) dissolving a preselected amount of a soluble metallic such as silver nitrate in the solution including ammonium soap to form a first solution; (c) adding a primary phase material such as a single phase YBC superconducting material in particle form to the first solution; (d) preparing a second solution formed from a mixture of a weak acid and an alkyl-mono-ether; (e) adding the second solution to the first solution to form a resultant mixture; (f) allowing the resultant mixture to set until the resultant mixture begins to cloud and thicken into a gel precipitating around individual particles of the primary phase material; (g) thereafter drying the resultant mixture to form a YBC superconducting material/silver nitrate precursor powder; and (h) calcining the YBC superconducting material/silver nitrate precursor powder to convert the silver nitrate to silver and thereby form a YBC/silver microcomposite powder wherein the silver is substantially uniformly dispersed in the matrix of the YBC material.

Maginnis, Michael A. (Coker, AL); Robinson, David A. (Mobile, AL)

1996-01-01T23:59:59.000Z

466

Microstructural Development in Al-Si Powder During Rapid Solidification  

SciTech Connect

Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications.

Amber Lynn Genau

2004-12-19T23:59:59.000Z

467

Dr. Xiaoping Wang | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Home › Contact Us › CV Home › Contact Us › CV Dr. Xiaoping Wang Instrument Scientist TOPAZ BL-12 Dr. Xiaoping Wang received his Ph.D. degree in inorganic chemistry from Texas A&M University in 1998, where he did his graduate work with Professor F. Albert Cotton. He then undertook postdoctoral research in neutron crystallography at Argonne National Laboratory. He was the director for crystallographic computing in the Laboratory for Molecular Structure and Bonding at Texas A&M University from December 2001 to May 2006; the director of X-Ray Diffraction Laboratory at University of North Texas from June 2006 to July 2008, and has been appointed as adjunct professor in the chemistry department. Dr. Wang is currently an instrument scientist co-responsible for the TOPAZ single crystal diffractometer (SNS

468

Quantitative description of microstructure defects in hexagonal boron nitrides using X-ray diffraction analysis  

SciTech Connect

A routine for simultaneous quantification of turbostratic disorder, amount of puckering and the dislocation and stacking fault density in hexagonal materials was proposed and tested on boron nitride powder samples that were synthesised using different methods. The routine allows the individual microstructure defects to be recognised according to their effect on the anisotropy of the X-ray diffraction line broadening. For quantification of the microstructure defects, the total line broadening is regarded as a linear combination of the contributions from the particular defects. The total line broadening is obtained from the line profile fitting. As testing material, graphitic boron nitride (h-BN) was employed in the form of hot-isostatically pressed h-BN, pyrolytic h-BN or a h-BN, which was chemically vapour deposited at a low temperature. The kind of the dominant microstructure defects determined from the broadening of the X-ray diffraction lines was verified by high resolution transmission electron microscopy. Their amount was attempted to be verified by alternative methods. - Highlights: Reliable method for quantification of microstructure defects in BN was suggested. The method is based on the analysis of anisotropic XRD line broadening. This XRD line broadening is unique and characteristic of the respective defect. Thus, the quantification of coexistent microstructure defects is possible. The method was tested on hexagonal BN, which was produced by different techniques.

Schimpf, C., E-mail: schimpf@iww.tu-freiberg.de; Motylenko, M.; Rafaja, D.

2013-12-15T23:59:59.000Z

469

Neutron-Neutron Scattering at Low Energies  

Science Journals Connector (OSTI)

This paper investigates the information contained in a neutron-neutron scattering experiment at low energies which could be performed by colliding beams coming from an underground nuclear explosion. The significance of such an experiment is discussed from the point of view of a check on charge symmetry and charge independence, and it is found that because of the electromagnetic complications in proton-proton scattering, and because of the proton-neutron mass difference, the knowledge of neutron-neutron scattering would be of considerable value. The functional form of the experimental data which is most convenient for analysis and the approximate relative magnitude of the terms is investigated, and it is concluded that for the kind of experiment which is envisaged (measuring cross sections to 10% from 20 keV to 2 MeV) only two parameters should be kept in the effective-range expansion. The connection between the number and distribution of energies at which the cross section is measured and the error on the individual measurements, on the one hand, and the accuracy of the effective-range parameters deduced from the experiments, on the other, is given explicitly and is found also to depend on the absolute magnitude of the scattering length. The results show that ten 10% measurements, suitably distributed between 20 keV and 2 MeV, can determine the sign of the scattering length to four standard deviations, the magnitude of the effective range to 50-70%, and the magnitude of the scattering length to about 3%. Finally, the relationship between the variation of the effective-range parameters and the corresponding variation in the parameters of the scattering potential is studied, and it is found that, while this relationship is strongly shape-dependent, a small change in the potential parameters, in any case, results in a large change in the scattering length, but a small one in the effective range. Numerical relationships show that, even in the worst case, the variation in the scattering length is about eight times the variation in the potential parameter. It is concluded that a 10% experiment at 20 energies between 20 keV and 2 MeV would be able to get information on the potential parameters sufficiently accurately so that charge-dependent or charge-symmetry violating effects could be detected.

Michael J. Moravcsik

1964-11-09T23:59:59.000Z

470

Texture analysis of silicon with an heterogeneous morphology used for the photovoltaic conversion by neutron diffraction  

E-Print Network (OSTI)

603 Texture analysis of silicon with an heterogeneous morphology used for the photovoltaic.10F - 61.14F 1. Introduction. In order to lower the production cost of solar cells, the Research perpendicularly to growth axis, which led to photovoltaic efficiency q ~ 11 % under AM1 conditions, starting

Paris-Sud XI, Université de

471

Neutron diffraction of. cap alpha. ,. beta. and. gamma. cyclodextrins: hydrogen bonding patterns  

SciTech Connect

Cyclodextrins (CD's) are torus-shaped molecules composed of six (..cap alpha..), seven (..beta..) or eight (..gamma..) (1 ..-->.. 4) linked glucoses. ..cap alpha..-CD has been shown to have two different structures with well-defined hydrogen bonds, one tense and the other relaxed. An induced-fit-like mechanism for ..cap alpha..-CD complex formation has been proposed. Circular hydrogen bond networks have also been found for ..cap alpha..-CD due to the energetically favored cooperative effect. ..beta..-CD with a disordered water structure possesses an unusual flip-flop hydrogen bonding system of the type O-H H-O representing an equilibrium between two states; O-H O reversible H-O. ..gamma..-CD with a disordered water structure similar to ..beta..-CD also possesses the flip-flop hydrogen bond. This study demonstrates that hydrogen bonds are operative in disordered systems and display dynamics even in the solid state.

Hingerty, B.E.; Klar, B.; Hardgrove, G.; Betzel, C.; Saenger, W.

1983-01-01T23:59:59.000Z

472

Cold drawn steel wires--processing, residual stresses and ductility Part II: Synchrotron and neutron diffraction  

E-Print Network (OSTI)

Cold drawn steel wires--processing, residual stresses and ductility Part II: Synchrotron Received in final form 29 September 2005 ABSTRACT Cold drawing of steel wires leads to an increase proposed that cold drawing would induce a phase transformation of the steel, possibly a martensitic

473

A low-temperature neutron diffraction study of Mn12-acetate  

Science Journals Connector (OSTI)

The low-temperature structure of the title dodecanuclear mixed-valence manganese carboxylate, [Mn12O12(CD3COO)16(H2O)4]2CD3COOH4H2O, is similar to the room-temperature structure, differing by a small change in the configuration of one of the coordinated acetate groups, related to additional hydrogen bonding.

Langan, P.

2001-08-09T23:59:59.000Z

474

Characterization of Li-ion Batteries using Neutron Diffraction and Infrared Imaging Techniques  

Energy.gov (U.S. Department of Energy (DOE))

2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation

475

Neutron Scattering and Diffraction Studies of Fluids and Fluid-Solid Interactions  

Science Journals Connector (OSTI)

...biopolymers, including proteins) and low-dimensional...scattering in partially disordered materials such as fluids...r-parameter is an ensemble average over the thermally...structure corresponds to the ensemble average for all molecules...volume) arises from an ensemble of snap shot images...

David R. Cole; Kenneth W. Herwig; Eugene Mamontov; John Z. Larese

476

Exclusive Diffractive Processes within the Dipole Picture  

E-Print Network (OSTI)

We discuss two different models for the impact parameter dependent dipole cross section: one based on DGLAP evolution and the other inspired by the Balitsky-Kovchegov equation. The parameters are determined from fits to data on the total gamma* p cross section measured at HERA. The impact parameter dependent saturation scale is extracted. Predictions are then confronted with HERA data on exclusive diffractive vector meson production and deeply virtual Compton scattering. Finally, predictions are given for the cross sections of exclusive photoproduced J/psi and Upsilon mesons, and Z^0 bosons, expected at the Tevatron and LHC.

G. Watt

2008-07-28T23:59:59.000Z

477

Exclusive Diffractive Processes within the Dipole Picture  

E-Print Network (OSTI)

We discuss two different models for the impact parameter dependent dipole cross section: one based on DGLAP evolution and the other inspired by the Balitsky-Kovchegov equation. The parameters are determined from fits to data on the total gamma* p cross section measured at HERA. The impact parameter dependent saturation scale is extracted. Predictions are then confronted with HERA data on exclusive diffractive vector meson production and deeply virtual Compton scattering. Finally, predictions are given for the cross sections of exclusive photoproduced J/psi and Upsilon mesons, and Z^0 bosons, expected at the Tevatron and LHC.

Watt, G

2008-01-01T23:59:59.000Z

478

Lessons from LHC elastic and diffractive data  

E-Print Network (OSTI)

In the light of LHC data, we discuss the global description of all high energy elastic and diffractive data, using a one-pomeron model, but including multi-pomeron interactions. The LHC data indicate the need of a $k_t(s)$ behaviour, where $k_t$ is the gluon transverse momentum along the partonic ladder structure which describes the pomeron. We also discuss tensions in the data, as well as the $t$ dependence of the slope of $d\\sigma_{el}/dt$ in the small $t$ domain.

A. D. Martin; V. A. Khoze; M. G. Ryskin

2014-10-13T23:59:59.000Z

479

Microsoft Word - Powder River Basin 1_6_06.doc  

NLE Websites -- All DOE Office Websites (Extended Search)

Economics of Powder River Basin Economics of Powder River Basin Coalbed Methane Development Prepared for: U.S. Department of Energy Prepared by: Gregory C. Bank Vello A. Kuuskraa vkuuskraa@adv-res.com Advanced Resources International, Inc. January 2006 Disclaimer This material was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. The Economics of Powder River Basin Coalbed Methane Development

480

Method and apparatus for the production of metal oxide powder  

DOE Patents (OSTI)

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

Harris, Michael T. (Knoxville, TN); Scott, Timothy C. (Knoxville, TN); Byers, Charles H. (Oak Ridge, TN)

1993-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "neutron powder diffraction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Method and apparatus for the production of metal oxide powder  

DOE Patents (OSTI)

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

Harris, Michael T. (Knoxville, TN); Scott, Timothy C. (Knoxville, TN); Byers, Charles H. (Oak Ridge, TN)

1992-01-01T23:59:59.000Z

482

Method and apparatus for the production of metal oxide powder  

DOE Patents (OSTI)

The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed. 2 figs.

Harris, M.T.; Scott, T.C.; Byers, C.H.

1992-06-16T23:59:59.000Z

483

Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust  

Science Journals Connector (OSTI)

We consider the astrophysical reaction rates for radiative neutron capture reactions (n,?) in the crust of a neutron star. The presence of degenerate neutrons at high densities (mainly in the inner crust) can drastically affect the reaction rates. Standard rates assuming a Maxwell-Boltzmann distribution for neutrons can underestimate the rates by several orders of magnitude. We derive simple analytical expressions for reaction rates at a variety of conditions with account for neutron degeneracy. We also discuss the plasma effects on the outgoing radiative transition channel in neutron radiative capture reactions and show that these effects can also increase the reaction rates by a few orders of magnitude. In addition, using detailed balance, we analyze the effects of neutron degeneracy and plasma physics on reverse (?,n) photodisintegration. We discuss the dependence of the reaction rates on temperature and neutron chemical potential and outline the efficiency of these reactions in the neutron star crust.

P. S. Shternin; M. Beard; M. Wiescher; D. G. Yakovlev

2012-07-24T23:59:59.000Z

484

Neutron-deuteron breakup reaction as a tool for studying neutron-neutron interactions  

SciTech Connect

An analysis of the most recent data on the reaction nd {yields} pnn revealed a serious discrepancy between theoretical predictions and cross sections measured for this reaction in various configurations where the role of neutron-neutron interactions is important. In view of this, it seems necessary both to develop theoretical approaches and to obtain new experimental data. For this purpose, a setup for studying the neutron-deuteron breakup reaction was created at the Institute for Nuclear Research on the basis of the neutron beam in the RADEX channel and deuterium targets. This facility makes it possible to perform experiments over a broad region of primary-neutron energies (10-60 MeV) and in various (final-state interaction, quasifree scattering, and spatial-star) configurations. Preliminary results of the respective experiment were obtained for configurations of final-state neutron-neutron interaction and quasifree neutron-neutron scattering.

Konobeevski, E. S., E-mail: konobeev@inr.ru; Zuyev, S. V.; Mordovskoy, M. V.; Potashev, S. I.; Sharapov, I. M. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)] [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

2013-11-15T23:59:59.000Z

485

Optical-diffraction method for determining crystal orientation  

DOE Patents (OSTI)

Disclosed is an optical diffraction technique for characterizing the three-dimensional orientation of a crystal sample. An arbitrary surface of the crystal sample is texture etched so as to generate a pseudo-periodic diffraction grating on the surface. A laser light beam is then directed onto the etched surface, and the reflected light forms a farfield diffraction pattern in reflection. Parameters of the diffraction pattern, such as the geometry and angular dispersion of the diffracted beam are then related to grating shape of the etched surface which is in turn related to crystal orientation. This technique may be used for examining polycrystalline silicon for use in solar cells.

Sopori, B.L.

1982-05-07T23:59:59.000Z

486

Neutron lifetime measurements using gravitationally trapped ultracold neutrons  

E-Print Network (OSTI)

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.

A. P. Serebrov; V. E. Varlamov; A. G. Kharitonov; A. K. Fomin; Yu. N. Pokotilovski; P. Geltenbort; I. A. Krasnoschekova; M. S. Lasakov; R. R. Taldaev; A. V. Vassiljev; O. M. Zherebtsov

2007-02-06T23:59:59.000Z

487

Novel neutron focusing mirrors for compact neutron sources  

E-Print Network (OSTI)

We demonstrated neutron beam focusing and neutron imaging using axisymmetric optics, based on pairs of confocal ellipsoid and hyperboloid mirrors. Such systems, known as Wolter mirrors, are commonly used in x-ray telescopes. ...

Gubarev, M.V.

488

Neutron skin of nuclei near the neutron drip line  

Science Journals Connector (OSTI)

Performing Skyrme-type deformed Hartree-Fock calculations, the possible presence of neutron skin in nuclei towards neutron drip line is studied. The thickness of the neutron skin is found to be nearly constant in all directions if it is measured perpendicular to the surface, and in a given nucleus the number of neutrons being inside of the neutron skin is almost independent of the deformation (namely, spherical shape or normal deformation or superdeformation). In the region of medium-heavy nuclei our calculation shows the presence of a series of neutron-rich nuclei, in which a neutron skin is present and yet the neutron one-particle spectra are far from those in a harmonic oscillator (plus spin-orbit) potential.

I. Hamamoto and X. Z. Zhang

1995-11-01T23:59:59.000Z

489

Neutron lifetime measurements using gravitationally trapped ultracold neutrons  

SciTech Connect

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before: the probability of UCN losses from the trap was only 1% of that for neutron {beta} decay. The neutron lifetime obtained, 878.5{+-}0.7{sub stat}{+-}0.3{sub sys} s, is the most accurate experimental measurement to date.

Serebrov, A. P.; Varlamov, V. E.; Kharitonov, A. G.; Fomin, A. K.; Krasnoschekova, I. A.; Lasakov, M. S.; Taldaev, R. R.; Vassiljev, A. V.; Zherebtsov, O. M. [Petersburg Nuclear Physics Institute, Russian Academy of Sciences, RU-188300 Gatchina, Leningrad District (Russian Federation); Pokotilovski, Yu. N. [Joint Institute for Nuclear Research, RU-141980 Dubna, Moscow Region (Russian Federation); Geltenbort, P. [Institut Max von Laue Paul Langevin, Boite Postal 156, F-38042 Grenoble Cedex 9 (France)

2008-09-15T23:59:59.000Z

490

Neutron Scattering Instrumentation for Biology at Spallation Neutron Sources  

Science Journals Connector (OSTI)

Conventional wisdom holds that since biological entities are large, they must be studied with cold neutrons, a domain in which reactor sources of neutrons are often supposed to be pre-eminent. ... fact, the curre...

Roger Pynn

1996-01-01T23:59:59.000Z

491

Electron-neutron scattering and transport properties of neutron stars  

E-Print Network (OSTI)

We show that electrons can couple to the neutron excitations in neutron stars and find that this can limit their contribution to the transport properties of dense matter, especially the shear viscosity. The coupling between electrons and neutrons is induced by protons in the core, and by ions in the crust. We calculate the effective electron-neutron interaction for the kinematics of relevance to the scattering of degenerate electrons at high density. We use this interaction to calculate the electron thermal conductivity, electrical conductivity, and shear viscosity in the neutron star inner crust, and in the core where we consider both normal and superfluid phases of neutron-rich matter. In some cases, particularly when protons are superconducting and neutrons are in their normal phase, we find that electron-neutron scattering can be more important than the other scattering mechanisms considered previously.

Bertoni, Bridget; Rrapaj, Ermal

2014-01-01T23:59:59.000Z

492

Powder synthesis and consolidation of thallium based high temperature superconductors  

SciTech Connect

Objective is to provide research samples of the Tl-based powders prepared by Rockwell's spray calciner. Target compositions were set at 1.1 Tl, 1 Ba, 1 Ca, 1.5 Cu and 1.1 Tl, 1.12 Ba, 1 Ca, 1.88 Cu. Three calciner runs were made. The Nomex bags were replaced with Gore-Tex bags. The system was operated continuously for 24 h, producing 1.7 kg HTSC powder. Problems with CO[sub 2], Tl volatility during sintering, etc., are discussed.

Gay, R.L. (Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.)

1990-06-23T23:59:59.000Z

493

Process for preparing fine grain titanium carbide powder  

DOE Patents (OSTI)

A method for preparing finely divided titanium carbide powder in which an organotitanate is reacted with a carbon precursor polymer to provide an admixture of the titanium and the polymer at a molecular-level due to a crosslinking reaction between the organotitanate and the polymer. The resulting gel is dried, pyrolyzed to drive off volatile components and provide carbon. The resulting solids are then heated at an elevated temperature to convert the titanium and carbon to high-purity titanium carbide powder in a submicron size range.

Janey, Mark A. (Concord, TN)

1986-01-01T23:59:59.000Z

494

The neutron identified: Sir James Chadwick  

Science Journals Connector (OSTI)

The neutron identified: Sir James Chadwick ... Uses source material to describe the discovery of the neutron by James Chadwick. ...

Alfred B. Garrett