Bulletin of the American Physical Society
80th Annual Meeting of the APS Southeastern Section
Volume 58, Number 17
Wednesday–Saturday, November 20–23, 2013; Bowling Green, Kentucky
Session EA: Neutron Scattering in Material Science |
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Chair: Edward J. Kintzel, Western Kentucky University Room: 5 |
Friday, November 22, 2013 8:30AM - 9:06AM |
EA.00001: Advances and opportunities for single crystal neutron diffraction Invited Speaker: Christina Hoffmann Two powerful neuron sources at the Oak Ridge National Laboratory, a continuous source (HFIR) and a pulsed source (SNS), offer an exciting suite of next generation instrumentation available for single crystal neutron diffraction (SCND) experiments. The spectrum ranges from traditional monochromatic to (time resolved) polychromatic instruments. A new time resolved neutron single crystal diffractometer is now available for open user access. Time resolved SCND is a powerful tool to sample reciprocal space in a highly effective manner by collecting discrete scattering data within a wide wavelength band. It is exquisitely suited to survey volumes of reciprocal space highly efficiently and provides instantaneous data of the crystal symmetry and crystal quality. Moreover, neutron and X-ray diffraction are complementary techniques. X-ray scattering emphasizes scattering contributions from heavy elements, whereas neutron scattering is equally sensitive to the light element contribution. This can be exploited to resolve hydrogen coordination to metals in metal-hydride compounds or large hydrogen-bonded-frameworks. Furthermore, isotopic substitution studies and magnetic structures can be investigated at the same time due the neutron's magnetic moment. In this contribution we will show recent examples of structure analysis and comparison of neutron data. [Preview Abstract] |
Friday, November 22, 2013 9:06AM - 9:42AM |
EA.00002: Recent Progress at the Oak Ridge National Laboratory's Neutron Facilities Invited Speaker: Kenneth Herwig Oak Ridge National Laboratory is home to two forefront neutron scattering user facilities, the High Flux Isotope Reactor and the Spallation Neutron Source (SNS). The neutron scattering instruments at these two facilities probe both the structure and dynamics of materials across a wide-range of science interests including biomaterials, physics, and materials sciences. The past several years have seen a dramatic increase in both capacity and science capabilities as new instruments have entered the user program and others have been significantly upgraded. This talk will describe some of the recent progress that has been made and present a few examples of the science that has been enabled. It will conclude with a look into the future that could include a second target station at the SNS optimized for probing slow dynamics and large length scales. [Preview Abstract] |
Friday, November 22, 2013 9:42AM - 10:18AM |
EA.00003: Advanced Neutron Imaging and Scattering Techniques Using Multiple Modalities and Contrast for Studying Natural and Advanced Materials Invited Speaker: Dayakar Penumadu Novel neutron imaging techniques, a majority of them using energy selective neutrons, now offer the possibility to study the microstructure of engineering materials. This work will summarize recent research on neutron imaging based on contrasts resulting from attenuation, phase, dark-field, and diffraction. The major collaborators and user facilities are identified to acknowledge their significant contributions to these studies. \begin{itemize} \item Strain mapping exploiting Bragg Edges will be discussed based on experiments performed at Helmholtz Zentrum Berlin (HZB: N. Kardjlov, A. Hilger, I. Manke; ESS: M. Strobl) using a tunable monochromator device, at ISIS (J. Kelleher) and LANSCE (Bj{\o}rn Clausen) using the time-of flight approach in collaboration with A. Tremsin (UC Berkley). \item Bragg Edge based neutron imaging was used to monitor TRansfomation Induced Plasticity (TRIP) effect and localization effects, which remain undetected by other techniques, have been noticed for the first time using high resolution setup at CONRAD. \item Three dimensional grain mapping techniques developed at synchrotron sources, such as 3D-XRD and Diffraction Contrats Tomography (DCT), just opened numerous new applications for studying crystalline materials. The extension of the technique to neutrons will be discussed and data taken at HZB and NIST (D. Hussey, D. Jacobson) in close collaboration with ESRF (W. Ludiwg, P. Reischig) will be shown. \item 3-D simulations of multi-phase flow through porous media and verification using high resolution x-ray and neutron tomography data obtained at HZB (N. Kardjlov, A. Hilger, I. Manke) and NIST (D. Hussey and D. Jacobson). Recent experiments using larger diameter specimens at coarser resolution using PSI (P. Vontobel and E. Lehmann) imaging facility will also be discussed. Combined modality of using X-rays to precisely define solid phase, use of neutrons to identify water phase, and both modalities to identify gas phase spatially and temporally shows much promise for studying transport through porous media type problems. \item The importance of efficient and gamma insensitive thin neutron scintillators with rapid decay time will be discussed. Promising polymeric scintillator films developed by Penumadu's group and characterized at CG-1 facility at Oak Ridge National Laboratory (H. Bilheux) will be presented. \end{itemize} Many of the measurement techniques are still in the development stage and the targeted presentation will also define the needs for further improvements, so that existing and future neutron imaging facilities will be beneficial for a diverse and broad user community. [Preview Abstract] |
Friday, November 22, 2013 10:18AM - 10:54AM |
EA.00004: Applications of neutron scattering to understanding structure and gas storage properties of metal-organic frameworks and related materials Invited Speaker: Craig Brown The development of nanostructured materials with predictable and controllable connectivity and functionalities has sparked a multitude of research directions. We have been studying emerging metal-organic framework (MOFs) systems and their adsorption properties for methane storage, carbon capture, gas separations and hydrogen storage. Neutron methods including powder diffraction, vibrational and rotational spectroscopy, and quasi-elastic scattering, are invaluable to advancing our understanding the performance (or lack of performance) of novel storage and adsorption systems. This will be illustrated by discussing several examples taken from our recent research involving both MOFs other microporous materials. [Preview Abstract] |
Friday, November 22, 2013 10:54AM - 11:00AM |
EA.00005: Break
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Friday, November 22, 2013 11:00AM - 11:36AM |
EA.00006: Effects of electric field on the proton dynamics in hydrated lysozyme Souleymane Diallo Neutron scattering is an ideal probe to study condensed matter. In particular, quasi-elastic incoherent neutron scattering (QENS) is a spectroscopic method suitable for the studies of diffusive motions occurring on the pico- to nano-second time scale. This scale matches very well with certain molecular relaxation processes in soft condensed matter. In this talk, I will present our recent QENS results on the dynamics of water molecules confined inside nanoporous silica pores and around lysozyme surface. In these measurements, we have explored the effects of static electric field on the diffusivity of water molecules. We observe a clear impact of electric field on the water molecules confined by the silica substrate, but there is comparatively little or no effect of the field on water around lysozyme. A possible scenario and implications will be discussed. [Preview Abstract] |
Friday, November 22, 2013 11:36AM - 12:12PM |
EA.00007: Neutron scattering and the van Hove function Invited Speaker: Takeshi Egami The basis for inelastic neutron scattering was laid by van Hove in his seminal paper in 1954. In this paper he showed that the dynamic structure factor we observe by inelastic scattering, S(Q, E), is related through the double Fourier-transform to the correlation function in space and time, g(r, t), the so-called van Hove function. This paper allowed us to interpret theoretically the results of inelastic scattering, and is widely known for this reason. However, the van Hove function itself has almost never been used. This is because in order to obtain it through the Fourier-transformation S(Q, E) has to be determined over a wide range of Q and E, which is difficult with the conventional triple-axis spectrometer, and also there has been no need to obtain the van Hove function. This is now changed because the chopper spectrometers used with the spallation source can determine S(Q, E) over a wide range of Q and E. We discuss how the van Hove function helps understanding the atomic dynamics of a liquid, and how this explains the viscosity of a liquid. [Preview Abstract] |
Friday, November 22, 2013 12:12PM - 12:48PM |
EA.00008: Techniques for revealing the structure of amorphous materials using neutrons Invited Speaker: Jacqueline Johnson Studying amorphous structure with neutrons is a versatile and wide reaching technique. Typically, study of amorphous materials is limited by short to medium range order. However, complementary x-ray studies or isotopic substitution enabling difference calculations allow great detail to be gleaned. Amorphous materials studied by the author and collaborators include polymers, carbon-containing materials, nano-particles, and numerous glasses that are mostly a subset of window glass. A background on techniques and their complementary nature will be given as well as the structure of polyethylene oxide, transition metals and rare-earth's in silicate glasses, and studies on nano-crystalline graphite oxide and selenium nano-particles. [Preview Abstract] |
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