bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of the Xia Scanning Photoemission Spectromicroscope for Element Identification on Material Surfaces
Authors: Ko Cheng-Hao , Kirz Janos , Ade Harald , Hulbert Steve , Johnson Erik , Anderson Erik 
Published: April 2011

AbstractThe Second Generation Scanning Photoemission Microscope at the beamline X1A of the National Synchrotron Light Source (NSLS), X1A SPEM II, is designed for spatially resolved elemental and chemical analysis by X-ray Photoelectron Spectroscopy (XPS) on material surfaces. Based on Fresnel Zone Plate (ZP) microfocusing techniques with the use of a bright and coherent photon source, this microscope is capable of acquiring XPS spectra from a small area irradiated by the focused beam and taking element-specific (using photopeaks) or chemical-state-specific (by detecting the chemical core level shifts) images with a spatial resolution defined by the focused spot size.
Characterization of Defect Structures in Lely 6H-SiC Single Crystals Using Synchrotron White Beam X-Ray Topography
Authors: Huang W. , Wang S. , Dudley M. , Neudeck P. , Powell J. A. , Fazi C. 
Published: April 2011

AbstractDefect structures in Lely SiC single crystals have been studied using synchrotron white beam X-ray topography. Basal plane dislocations and stacking faults probably generated during post-growth cooling are clearly revealed. For both perfect dislocations and partial dislocations bounding the stacking faults, Burgers vectors and line directions are determined from contrast extinction analysis as well as projected direction analysis on different topographic images. The fault planes and fault vectors of the stacking faults were determined using contrast extinction analysis. Possible dislocation generation mechanisms are briefly discussed.
Extended X-Ray Absorption Fine Structure Studies of MnZn-Ferrite Films
Authors: Dorsey Paul C. , Harris Vincent G. , Chrisey Douglas B. , Lubitz Peter , Horwitz James S. , Koon Norman C. 
Published: April 2011

AbstractThe magnetic properties of MnZn-ferrite are greatly affected by the distribution and valence state of the magnetic and nonmagnetic metallic ions on the tetrahedral (A) and octahedral (B) sites in the spinel ferrite unit cell. A primary factor which can affect the distribution and valence state of the metallic ions is the stoichiometry of the ferrite. In this paper we report on the results of the site occupancy of the transition metal ions in a series of MnZn-ferrite films using extended x-ray absorption fine structure (EXAFS). The EXAFS data are correlated with the film composition and those magnetic properties which are sensitive to the ionic distribution (e.g., magnetic anisotropy field and magnetization) in order to confirm the use of EXAFS as a technique for the investigation of metallic ion distribution in spinel ferrites.
Magnetic and Structural Properties of Fe/Pd Multilayers Studied by Magnetic X-Ray Dichroism and X-Ray Absorption Spectroscopy
Authors: Mini S. M. , Fullerton Eric E. , Fontaine A. , Sowers C. H. , Bommannavar A. S. , Traverse A. , Baudelet F. , Pizzini S. 
Published: April 2011

AbstractThe results of magnetic circular x-ray dichroism (MCXD) measurements and extended x-ray absorption fine structure measurements (EXAFS) of the Fe K-edges of textured Fe(110)/Pd(111) multilayers are reported. The EXAFS results indicates that the iron in the system goes from bcc to a more densely packed system as the thickness of the iron layer is decreased. The magnetic properties were measured by SQUID magnetometry from 5 - 350 K. For all the samples, the saturation magnetization was significantly enhanced over the bulk values indicating the interface Pd atoms are polarized by the Fe layer. The enhancement corresponds to a moment of ≈2.5μB per interface Pd atom.
Materials Science Applications of the New National Institute of Standards and Technology Powder Diffractometer
Authors: Stalick J. K. , Prince E. , Santoro A. , Schroder I. G. , Rush J. J. 
Published: April 2011

ABSTRACTThe new high-resolution neutron powder diffractometer BT-1 at the NIST reactor has proven to be a powerful and versatile instrument in its first year of operation. With 32 detectors arranged at 5° intervals and a 12° 2θ scan range, powder diffraction patterns can be collected to 167° 2θ. There is a choice of three monochromator take-off angles (75°, 90°, and 120°) so that the peak-width minimum can be matched to the rf-spacing range that is most important for each sample; all choices have a wavelength close to 1.54 Å. Data can be collected on sample sizes ranging from 200 mg to 30 g. Temperatures of 0.3 K to 1400 K are routinely available, and a magnetic field of 7T can be applied with a superconducting magnet. Typical data collection times range from 1-12 hours depending upon sample size and desired resolution. Examples are given of a variety of materials applications.
The Multiple Disk Chopper Neutron Time-of-Flight Spectrometer at Nist
Authors: Altorfer Felix B. , Cook Jeremy C. , Copley John R. D. 
Published: April 2011

ABSTRACTA highly versatile multiple disk chopper neutron time-of-flight spectrometer is being installed at the Cold Neutron Research Facility of the National Institute of Standards and Technology. This new instrument will fill an important gap in the portfolio of neutron inelastic scattering spectrometers in North America. It will be used for a wide variety of experiments such as studies of magnetic and vibrational excitations, tunneling spectroscopy, and quasielastic neutron scattering investigations of local and translational diffusion. The instrument uses disk choppers to monochromate and pulse the incident beam, and the energy changes of scattered neutrons are determined from their times-of-flight to a large array of detectors. The disks and the guide have been designed to make the instrument readily adaptable to the specific performance requirements of experimenters. We present important aspects of the design, as well as estimated values of the flux at the sample and the energy resolution for elastic scattering. The instrument should be operational in 1996.
Non-Standard Fickian Self-Diffusion of Isotopically Pure Boron Observed by Neutron Reflectometry and Depth Profiling
Authors: Baker Shenda M. , Wu K. , Smith G. S. , Hubbard K. M. , Nastasi M. , Downing R. G. , Lamaze G. P. 
Published: April 2011

ABSTRACTNeutron reflectometry (NR) studies1 of thin films of amorphous 11B/l0B on silicon indicate that a non-standard form of Fickian diffusion occurs across the boron interface upon annealing. In order to verify this observation, the samples were examined by neutron depth profiling (NDP). Comparison of the results from models of a step function, standard Fickian diffusion and Fickian diffusion with a fixed composition at the interface were made and compared to the previous NR results. The diffusion constant resulting from the non-standard Fickian model for the NDP data differs slightly from that obtained from the commonly used Fickian diffusion model and is not inconsistent with the NR results. This finding suggests that more information regarding diffusion at interfaces can be gained from these higher resolution neutron scattering techniques.
Growth and Dissolution of Protective Oxide Films on Titanium: an in-Situ Neutron Reflectivity Study
Authors: Wlesler D.G. , Majkrzak C.F. 
Published: April 2011

ABSTRACTThe structure and morphology of titanium thin film electrodes have been investigated by neutron reflectometry. This technique yields a detailed depth profile of the scattering density, which is used to determine hydrogen and oxygen concentration profiles within the electrode. By depositing the electrode on a thick silicon crystal window, we are able to monitor the growth and dissolution of the protective oxide film covering the titanium as a function of time, electrode potential, and electrolyte composition. We find that, in 0.1 N sulfuric acid, the oxide dissolves at 0.7 A/h and is self-healing, meaning that as the oxide dissolves the metal underneath is oxidized to maintain a protective barrier. In contrast, when a -2 V cathodic bias is applied to a passive film, the oxide thins with no compensating oxide growth underneath, and the film undergoes electrochemical breakdown.
Collapse of Isolated Chains in a Network
Authors: Briber R. M. , Liu X. , Bauer B.J. 
Published: April 2011

ABSTRACTIn this study we use small angle neutron scattering to investigate the conformation of linear deuterated polystyrene chains trapped in a crosslinked protonated polystyrene matrix. The second virial coefficient was obtained as a function of crosslink density for a wide range of crosslink density. It is shown that the second virial coefficient decreases with increasing crosslink density. By extrapolating the scattering to zero concentration of the linear chain at all values of q, the single chain scattering was obtained and radius of gyration was measured the function of network density. It was found that when the network density is low (NI < Nc where NI and Nc are the number of monomer units in the linear chain and the monomer units between crosslinks, respectively) the radius of gyration does not change. As the network density increases (NI > Nc ) radius of gyration decreases. In this region the inverse of the radius of gyration varies linearly with the inverse of Nc. When the crosslink density is very high (NI » Nc ), segregation of linear polymer chains occurs. These results are in agreement with prediction and computer simulation results of polymer chain conformation in a field of random obstacles where the crosslink junctions act as the effective obstacles.
Sans Study of Phase Separation in Solid 3He-4He
Authors: Koster J.P. , Nagler S.E. , Adams E.D. , Wignall G.D. 
Published: April 2011

ABSTRACTSmall angle neutron scattering has been used to study phase separation in a quantum alloy, solid 3Hex-4He1-x. The onset of phase separation is marked by a dramatic increase in the measured scattering. A simple interpretation of the results suggests that the late-stage phase separation kinetics are dominated by an increase in the concentration of 3He atoms in preexisting precipitate regions.
Neutron Scattering from a Ferrofluid
Authors: Lin Min Y. , Luo Weili , Lynn Jeffrey 
Published: April 2011

ABSTRACTSmall angle neutron scattering experiments were performed on a eicosane-based ferrofluid. An average size of 88 Å can be extracted from the data, in agreement with results from electron microscopy. Below the frozen temperature of eicosane, however, the particles are seen to be in larger aggregates with a fractal dimension of 2.15, similar to those formed under reaction-limited cluster aggregation (RLCA) conditions. At high concentrations, particles form larger aggregates even in the liquid state. Applying a magnetic field introduces new structure and changes the density inside the aggregates.
New Developments in Multiple Small-Angle Neutron Scattering Studies of Advanced Ceramics
Authors: Allen Andrew J. , Berk Norman F. , Krueger Susan , Long Gabrielle G. , Kerch Helen M. , Ilavsky Jan 
Published: April 2011

ABSTRACTAn enhanced multiple small-angle neutron scattering (MSANS) formulation has been developed to interpret the beam-broadening, arising from coarse, concentrated pore/grain microstructures in porous ceramics and similar materials. Prolific scattering from such systems precludes single-scattering studies (apart from Porod surface determinations). Previous MSANS techniques, which have been developed to extract the mean pore dimensions, either treat a range of scattering morphologies, while assuming that the scattering is in the diffraction limit, or they consider refraction effects, while assuming that the scattering features are spherical. Many systems of interest violate both these assumptions. In the enhanced formulation, the previous method, which allowed fully for refraction, is extended to non-spherical scattering morphologies. Applications of the MSANS formulation to sintering studies of Si3N4 and silica gels, and to the microstructural characterization of plasma-spray coatings are currently of interest.
Analyses of Creep Pores in Liquid-Phase-Sintered Alumina by Means of Joint Use of Conventional and High-Resolution Sans
Authors: Klatt M. , Bellmann D. , Kampmann R. , Wagner R. , Wolf C. , HÜbner H. 
Published: April 2011

ABSTRACTFailure of ceramic materials for high-temperature applications is initiated by the formation of creep pores. Thus, the determination of the sizes and number densities of pores induced during creep testing is one key to a understanding of their failure mechanisms and related life-time predictions. For this purpose small-angle neutron scattering (SANS) techniques are one of the most potential tools as demonstrated by an analysis of creep pores in liquid-phase-sintered, hot isostatically pressed alumina. The exploration of creep induced pores requires the analysis of SANS intensity over an extremely extended region of scattering vectors, the scanning of which needs joint use of both conventional SANS and double crystal diffractometry (DCD), an ultra small angle scattering technique.
The Determination of Macrostresses (Type-I Stresses) and Microstresses (Type-Ii Stresses) by Neutron Diffraction
Authors: Holden T.M. 
Published: April 2011

ABSTRACTNeutron diffraction has been used as tool for measuring stress fields (type-I stresses) and intergranular or microstresses (type-II stresses) for a decade. The experimental methods for measuring the two types of stresses are outlined. Emphasis is placed on maximizing the precision and accuracy of the measurements. Some serious sources of error in measurements near surfaces and some subtle wavelength effects are considered.
Micro Stresses in Welded High-Strength Stainless Steels
Authors: LukÁš P. , Janovec J. , Macek K. , Mikula P. , Strunz P. , VrÁna M. , Zaffagnini M. 
Published: April 2011

ABSTRACTThe dependence of residual stresses in martensitic-austenitic age-hardenable steels on a different technological treatment (welding by electron beam, postweld heat treatment) were investigated using a neutron diffraction. Experiments were performed in NPI Řež on a high-resolution diffractometer equipped with cylindrically bent perfect crystals. The resolution of the instrument (Δd/d ≈ 10-4; d-lattice spacing) enabled us to investigate plastic strains in weld joints.
Neutron Powder Diffraction Refinement of the Nuclear and Magnetic Structures of HoNi2B2C at R.T., 10, 5.1 AND 2.2 K
Authors: Huang Q. , Santoro A. , Grigereit T.E. , Lynn J.W. , Cava R.J. , Krajewski J.J. , Peck W.F. 
Published: April 2011

ABSTRACTThe nuclear and magnetic structures of HoNi2B2C have been investigated by neutron powder diffraction at room temperature and at 10, 5.1 and 2.2K. The compound crystallizes with the symmetry of space group 14/mmm and has room temperature lattice parameters a=3.5170(1) and c=10.5217(3) Å. No phase transitions of the nuclear structure have been observed in the range of temperatures examined. Magnetic peaks begin to appear at about 8K. The magnetic structure is the superposition of two configurations, one in which ferromagnetic sheets of holmium spins parallel to the a-b plane are coupled antiferromagnetically along the c-axis, and another in which the ferromagnetic planes are rotated away from the antiparallel configuration to give an incommensurate helicoidal structure with a period approximately equal to twelve times the length of the c-axis. The helicoidal structure competes with superconductivity while the antiferromagnetism coexists with it.
Investigation of Magnetic Structure of MnTe/CdTe Multilayers by Neutron Diffraction
Authors: Nunez V. , Giebultowicz T. M. , Faschinger W. , Bauer G. , Sitter H. , Furdyna J. K. 
Published: April 2011

ABSTRACTNeutron-diffraction studies of MnTe/CdTe superlattices with very thin CdTe spacers are reported. Results indicate the formation of spin helices (consistent with the tensile nature of strain in the MnTe layers) and coherence between the helices in different MnTe layers. Possible mechanisms for the interlayer correlations are discussed.
Neutron Scattering Study of the Magnetism in a Nanocrystalline/Amorphous Material
Authors: Rosov N. , Lynn J. W. , Fish G. E. 
Published: April 2011

ABSTRACTRecently developed nanocrystalline magnetic systems are of considerable interest fundamentally as well as technologically. One such material is Fe73.5B9Si13.5Cu1Nb3, which can be produced by heat treating the amorphous precursor. This forms a noncrystalline phase with typical dimension of 350 A as determined by neutron diffraction. Small angle neutron scattering (SANS) has been employed to investigate the properties of the nanocrystallized material over the temperature range from 10 K to 725 K, a regime where no significant structural changes are expected to occur. In zero field and low temperature (10K) we obtained an isotropic scattering pattern. The application of a relatively modest field to sweep out the domains changed the scattering to a "butterfly wings" pattern typical of patterns dominated by magnetic elastic intensity. Up to 450 K this pattern changed only modestly, while for substantially higher temperatures the ratio of inelastic to elastic scattering increased rapidly as the magnetic phase transition of the intergranular component (≃ 575 K) was approached. Triple axis inelastic measurements showed that the majority of the magnetic inelastic scattering was from the nanocrystalline phase.
Structures and Magnetic Properties of a Family of One-Dimensional Oxides, Sr3M′M″06 (M′ = Co, Ni, Zn and M″ = Pt, Ir)
Authors: Nguyen TU N. , Zur Loye Hans-Conrad 
Published: April 2011

ABSTRACTA family of one-dimensional oxides was synthesized by solid state techniques and their structures determined by powder X-ray and powder neutron Rietveld refinement. The compounds are structurally related to A4PtO6 (A = Ca, Sr, Ba), which contains infinite chains of alternating face-sharing PtO6 octahedra and AO6, trigonal prisms. The compounds exhibit a variety of magnetic properties. The structures and magnetic properties of some of these one-dimensional oxides are discussed.
Neutron Scattering Study of Vibrational Modes in Glassy Gel-xSnxSe2
Authors: Cappelletti R. L. , Kamitakahara W.A. , Islam Didarul 
Published: April 2011

ABSTRACTThe neutron vibrational density of states has been determined from neutron time-of-flight scattering in g-Ge1-xSnxSe2 with x = 0, 0.3, 0.35, and 0.5 to search for "floppy" modes. Previously Raman and Mossbauer studies1 have been interpreted on the basis that the addition of Sn to the GeSe2 network reduces the average number of mechanical constraints per atom allowing one to tune through the rigidity percolation threshold near x = 0.35. A comparison of the VDOS measured in this work below 10 meV for all samples shows that they are nearly identical indicating no evidence of the existence of floppy modes in these samples. Ab initio molecular dynamics2 calculations of the VDOS show good agreement with the measured results for g-GeSe2.
Spin-Density-Wave Magnetism in Dilute Copper-Manganese Alloys
Authors: Lamelas F. J. , Werner S. A. , Shapiro S. M. , Mydosh J. A. 
Published: April 2011

ABSTRACTElastic neutron-scattering measurements on two samples of Cu alloyed with 1.3% Mn and 0.55% Mn show that the spin-density-wave (SDW) features found in more concentrated alloys persist in the limit of very dilute alloys. These features consist of temperature-dependent incommensurate peaks in magnetic neutron scattering, with positions and strengths which are fully consistent with those in the concentrated alloys. The implications of these measurements are twofold. First, it is clear from our data that SDW magnetic ordering occurs across the entire range of CuMn alloys which have typically been interpreted as spin glasses. Second, the more fundamental significance of this work is the suggestion via extrapolation that a peak in the magnetic susceptibility χ(q) occurs in pure copper, at a value of q given by the Fermi-surface diameter 2kF.
Inelastic Neutron Scattering by Pristine And Doped Phases of Polyacetylene
Authors: Papanek P. , Fischer J. E. , Sauvajou J. L. , Dianoux A. J. , Mcneillis P. M. , Mathis C. , Francois B. 
Published: April 2011

ABSTRACTInelastic incoherent neutron-scattering spectra of cis-, trans- and Na-doped polyacety-lene are presented. The experiments were performed with time-of-flight and filter-analyzer spectrometers on stretch-oriented samples such that the polarization of vibrational modes could also be determined.
Orientational Dynamcs in White Phosphorus (P4)
Authors: Kamitakahara W.A. , Gompf F. , Neumann D.A. 
Published: April 2011

ABSTRACTAbove To = 196 K, white phosphorus, a solid composed of P4 molecules, exhibits a plastic crystal phase. Below this temperature, the structure is triclinic and orientationally ordered, with six molecules in a unit cell. Using inelastic neutron scattering on a polycrystalline sample, observations were made of the rapid reorientational motions above To, and the librational modes below To. In addition, neutron powder diffraction was used to investigate the crystal structures above and below To.
Neutron Scattering, Momentum Distributions and Final State Effects
Authors: Glyde Henry R. 
Published: April 2011

ABSTRACTInelastic neutron scattering measurements of the atomic momentum distribution, the atomic kinetic energy and other single atom properties in quantum liquids and liquid neon are presented. The data were taken on the MARI instrument at ISIS and analyzed using a new method. The measurements have sufficient precision to show that n(k) in a normal Bose liquid differs significantly and unambiguously from the classical, Maxwell-Boltzmann distribution. The final state broadening function is also extracted from the data and found to be similar in liquid 3He and 4He.
Small Angle Neutron Scattering at Mcmaster University
Authors: Avelar J.M. , Mason P.C. , Gaulin B.D. , Copley J.R.D. 
Published: April 2011

ABSTRACTWe describe the Small Angle Neutron Scattering spectrometer at McMaster University. We then discuss three examples of recent studies using this instrument: (1) the membrane-water interface in multilamellar vesicles; (2) magnetic ordering of Ni0.8Co0.2/Cu multilayers; and (3) precipitate sizes in titanium stabilized interstitial-free steels.
Small-Angle Neutron Scattering in a High-Temperature Furnace
Authors: Long G.G. , Kerch H.M. , Krueger S. , Allen A.J. , Burdette H. 
Published: April 2011

ABSTRACTSmall-angle neutron scattering (SANS) is increasingly used to obtain statistically-representative data on particle or pore sizes, number and volume fractions, morphology and total surface areas in technological materials. Until recently, however, it had not been possible to perform in-situ microstructural investigations during thermal treatment. This paper reports on a new high-temperature (up to 1700°C) SANS furnace for materials research. Two interchangeable inner furnaces were built for a single outer atmosphere chamber so that either an oxidizing, a reducing, or a neutral environment can be used. Results derived during sintering of a controlled-porosity silica gel will be presented. The new furnace has made it possible for the first time to measure total porous surface areas and the evolution of pore sizes in situ during densification without interruption. Such measurements are expected to lead to improved process models offering quantitative predictability of product microstructures from the processing history of real materials.