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Journal of Applied Crystallography

Stephan Niebling, Alexander Björling, Sebastian Westenhoff
[This corrects the article DOI: 10.1107/S1600576714009959.].
June 1, 2018: Journal of Applied Crystallography
Sven C Vogel, Chris M Biwer, David H Rogers, James P Ahrens, Robert E Hackenberg, Drew Onken, Jianzhong Zhang
A tool named Cinema:Debye-Scherrer to visualize the results of a series of Rietveld analyses is presented. The multi-axis visualization of the high-dimensional data sets resulting from powder diffraction analyses allows identification of analysis problems, prediction of suitable starting values, identification of gaps in the experimental parameter space and acceleration of scientific insight from the experimental data. The tool is demonstrated with analysis results from 59 U-Nb alloy samples with different compositions, annealing times and annealing temperatures as well as with a high-temperature study of the crystal structure of CsPbBr3 ...
June 1, 2018: Journal of Applied Crystallography
P Scardi, M Ermrich, A Fitch, E-Wen Huang, R Jardin, R Kuzel, A Leineweber, A Mendoza Cuevas, S T Misture, L Rebuffi, Christian Schimpf
Separation of size and strain effects on diffraction line profiles has been studied in a round robin involving laboratory instruments and synchrotron radiation beamlines operating with different radiation, optics, detectors and experimental configurations. The studied sample, an extensively ball milled iron alloy powder, provides an ideal test case, as domain size broadening and strain broadening are of comparable size. The high energy available at some synchrotron radiation beamlines provides the best conditions for an accurate analysis of the line profiles, as the size-strain separation clearly benefits from a large number of Bragg peaks in the pattern; high counts, reliable intensity values in low-absorption conditions, smooth background and data collection at different temperatures also support the possibility to include diffuse scattering in the analysis, for the most reliable assessment of the line broadening effect...
June 1, 2018: Journal of Applied Crystallography
Pingguang Xu, Stefanus Harjo, Mayumi Ojima, Hiroshi Suzuki, Takayoshi Ito, Wu Gong, Sven C Vogel, Junya Inoue, Yo Tomota, Kazuya Aizawa, Koichi Akita
Neutron diffraction texture measurements provide bulk averaged textures with excellent grain orientation statistics, even for large-grained materials, owing to the probed volume being of the order of 1 cm3 . Furthermore, crystallographic parameters and other valuable microstructure information such as phase fraction, coherent crystallite size, root-mean-square microstrain, macroscopic or intergranular strain and stress, etc. can be derived from neutron diffractograms. A procedure for combined high stereographic resolution texture and residual stress evaluation was established on the pulsed-neutron-source-based engineering materials diffractometer TAKUMI at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Center, through division of the neutron detector panel regions...
June 1, 2018: Journal of Applied Crystallography
Marianna Marciszko, Andrzej Baczmański, Manuela Klaus, Christoph Genzel, Adrian Oponowicz, Sebastian Wroński, Mirosław Wróbel, Chedly Braham, Habib Sidhom, Roman Wawszczak
The main focus of the presented work was the investigation of structure and residual stress gradients in the near-surface region of materials studied by X-ray diffraction. The multireflection method was used to measure depth-dependent stress variation in near-surface layers of a Ti sample (grade 2) subjected to different mechanical treatments. First, the multireflection grazing incidence diffraction method was applied on a classical diffractometer with Cu  K α radiation. The applicability of the method was then extended by using a white synchrotron beam during an energy dispersive (ED) diffraction experiment...
June 1, 2018: Journal of Applied Crystallography
Weiwei Wang, A Dominic Fortes, David P Dobson, Christopher M Howard, John Bowles, Neil J Hughes, Ian G Wood
An apparatus is described for the compression of samples to ∼2 GPa at temperatures from 80 to 300 K, rapid chilling to 80 K whilst under load and subsequent recovery into liquid nitro-gen after the load is released. In this way, a variety of quenchable high-pressure phases of many materials may be preserved for examination outside the high-pressure sample environment, with the principal benefit being the ability to obtain high-resolution powder diffraction data for phase identification and structure solution...
June 1, 2018: Journal of Applied Crystallography
Ian G Wood, A Dominic Fortes, David P Dobson, Weiwei Wang, Lucjan Pajdzik, John Cosier
A low-temperature stage for X-ray powder diffraction in Bragg-Brentano reflection geometry is described. The temperature range covered is 40-315 K, with a temperature stability at the sample within ±0.1 K of the set point. The stage operates by means of a Gifford-McMahon (GM) closed-cycle He refrigerator; it requires no refrigerants and so can run for an extended period (in practice at least 5 d) without intervention by the user. The sample is cooled both by thermal conduction through the metal sample holder and by the presence of He exchange gas, at ambient pressure, within the sample chamber; the consumption of He gas is extremely low, being only 0...
June 1, 2018: Journal of Applied Crystallography
Stefan Mattauch, Alexandros Koutsioubas, Ulrich Rücker, Denis Korolkov, Vicenzo Fracassi, Jos Daemen, Ralf Schmitz, Klaus Bussmann, Frank Suxdorf, Michael Wagener, Peter Kämmerling, Harald Kleines, Lydia Fleischhauer-Fuß, Manfred Bednareck, Vladimir Ossoviy, Andreas Nebel, Peter Stronciwilk, Simon Staringer, Marko Gödel, Alfred Richter, Harald Kusche, Thomas Kohnke, Alexander Ioffe, Earl Babcock, Zahir Salhi, Thomas Bruckel
MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and biology. The elliptical vertically focusing guide allows one to measure small samples with a typical size of 1 × 1 cm very efficiently. The double-bounce polarizer and the in situ pumped 3 He SEOP (spin-exchange optical pumping) neutron spin filter cell for analysing the polarization of the reflected neutron beam can be moved into the beam in seconds...
June 1, 2018: Journal of Applied Crystallography
Michael Heere, Martin J Mühlbauer, Alexander Schökel, Michael Knapp, Helmut Ehrenberg, Anatoliy Senyshyn
The need for rapid data collection and studies of small sample volumes in the range of cubic millimetres are the main driving forces for the concept of a new high-throughput monochromatic diffraction instrument at the Heinz Maier-Leibnitz Zentrum (MLZ), Germany. A large region of reciprocal space will be accessed by a detector with sufficient dynamic range and microsecond time resolution, while allowing for a variety of complementary sample environments. The medium-resolution neutron powder diffraction option for 'energy research with neutrons' (ErwiN) at the high-flux FRM II neutron source at the MLZ is foreseen to meet future demand...
June 1, 2018: Journal of Applied Crystallography
Carlos G Lopez, Takaichi Watanabe, Marco Adamo, Anne Martel, Lionel Porcar, João T Cabral
A comparative examination is presented of materials and approaches for the fabrication of microfluidic devices for small-angle neutron scattering (SANS). Representative inorganic glasses, metals, and polymer materials and devices are evaluated under typical SANS configurations. Performance criteria include neutron absorption, scattering background and activation, as well as spatial resolution, chemical compatibility and pressure resistance, and also cost, durability and manufacturability. Closed-face polymer photolithography between boron-free glass (or quartz) plates emerges as an attractive approach for rapidly prototyped microfluidic SANS devices, with transmissions up to ∼98% and background similar to a standard liquid cell ( I ≃ 10-3  cm-1 )...
June 1, 2018: Journal of Applied Crystallography
Kathryn L Shelley, Thomas P E Dixon, Jonathan C Brooks-Bartlett, Elspeth F Garman
Radiation damage remains one of the major limitations to accurate structure determination in protein crystallography (PX). Despite the use of cryo-cooling techniques, it is highly probable that a number of the structures deposited in the Protein Data Bank (PDB) have suffered substantial radiation damage as a result of the high flux densities of third generation synchrotron X-ray sources. Whereas the effects of global damage upon diffraction pattern reflection intensities are readily detectable, traditionally the (earlier onset) site-specific structural changes induced by radiation damage have proven difficult to identify within individual PX structures...
April 1, 2018: Journal of Applied Crystallography
Martha G Pamato, Ian G Wood, David P Dobson, Simon A Hunt, Lidunka Vočadlo
On the basis of ab initio computer simulations, pre-melting phenomena have been suggested to occur in the elastic properties of hexagonal close-packed iron under the conditions of the Earth's inner core just before melting. The extent to which these pre-melting effects might also occur in the physical properties of face-centred cubic metals has been investigated here under more experimentally accessible conditions for gold, allowing for comparison with future computer simulations of this material. The thermal expansion of gold has been determined by X-ray powder diffraction from 40 K up to the melting point (1337 K)...
April 1, 2018: Journal of Applied Crystallography
M Raventós, E H Lehmann, M Boin, M Morgano, J Hovind, R Harti, J Valsecchi, A Kaestner, C Carminati, P Boillat, P Trtik, F Schmid, M Siegwart, D Mannes, M Strobl, C Grünzweig
The development of neutron imaging from a qualitative inspection tool towards a quantitative technique in materials science has increased the requirements for accuracy significantly. Quantifying the thickness or the density of polycrystalline samples with high accuracy using neutron imaging has two main problems: (i) the scattering from the sample creates artefacts on the image and (ii) there is a lack of specific reference attenuation coefficients. This work presents experimental and simulation results to explain and approach these problems...
April 1, 2018: Journal of Applied Crystallography
Judith Elizabeth Houston, Georg Brandl, Matthias Drochner, Günter Kemmerling, Ralf Engels, Aristeidis Papagiannopoulos, Mona Sarter, Andreas Stadler, Aurel Radulescu
A new detection system based on an array of 3 He tubes and innovative fast detection electronics has been installed on the high-intensity small-angle neutron scattering (SANS) diffractometer KWS-2 operated by the Jülich Centre for Neutron Science (JCNS) at the Heinz Meier-Leibnitz Zentrum in Garching, Germany. The new detection system is composed of 18 eight-pack modules of 3 He tubes that work independently of one another (each unit has its own processor and electronics). To improve the read-out characteristics and reduce the noise, the detection electronics are mounted in a closed case on the rear of the 3 He tubes' frame...
April 1, 2018: Journal of Applied Crystallography
Feng Ye, Yaohua Liu, Ross Whitfield, Ray Osborn, Stephan Rosenkranz
The CORELLI instrument at Oak Ridge National Laboratory is a statistical chopper spectrometer designed and optimized to probe complex disorder in crystalline materials through diffuse scattering experiments. On CORELLI, the high efficiency of white-beam Laue diffraction combined with elastic discrimination have enabled an unprecedented data collection rate to obtain both the total and the elastic-only scattering over a large volume of reciprocal space from a single measurement. To achieve this, CORELLI is equipped with a statistical chopper to modulate the incoming neutron beam quasi-randomly, and then the cross-correlation method is applied to reconstruct the elastic component from the scattering data...
April 1, 2018: Journal of Applied Crystallography
Ken Holst Andersen, Mads Bertelsen, Luca Zanini, Esben Bryndt Klinkby, Troels Schönfeldt, Phillip Martin Bentley, Jan Saroun
A global approach coupling the moderator to the beam extraction system has been applied for the design optimization of the thermal and cold moderators of the European Spallation Source (ESS), which will be the brightest neutron source in the world for condensed-matter studies. The design is based on the recently developed high-brightness low-dimensional moderator concepts. Para -hydrogen is used for the cold neutron source, while thermal neutrons are provided by moderation in water. The overall moderation configuration was chosen in order to satisfy a range of requirements on bispectral extraction, beamport configuration and instrument performance...
April 1, 2018: Journal of Applied Crystallography
Ross N Andrews, Suresh Narayanan, Fan Zhang, Ivan Kuzmenko, Jan Ilavsky
X-ray photon correlation spectroscopy (XPCS) and dynamic light scattering (DLS) both reveal dynamics using coherent scattering, but X-rays permit investigating of dynamics in a much more diverse array of materials. Heterogeneous dynamics occur in many such materials, and we showed how classic tools employed in analysis of heterogeneous DLS dynamics extend to XPCS, revealing additional information that conventional Kohlrausch exponential fitting obscures. This work presents the software implementation of inverse transform analysis of XPCS data called CONTIN XPCS, an extension of traditional CONTIN that accommodates dynamics encountered in equilibrium XPCS measurements...
February 2018: Journal of Applied Crystallography
Ross N Andrews, Suresh Narayanan, Fan Zhang, Ivan Kuzmenko, Jan Ilavsky
X-ray photon correlation spectroscopy (XPCS), an extension of dynamic light scattering (DLS) in the X-ray regime, detects temporal intensity fluctuations of coherent speckles and provides scattering vector-dependent sample dynamics at length scales smaller than DLS. The penetrating power of X-rays enables probing dynamics in a broad array of materials with XPCS, including polymers, glasses and metal alloys, where attempts to describe the dynamics with a simple exponential fit usually fails. In these cases, the prevailing XPCS data analysis approach employs stretched or compressed exponential decay functions (Kohlrausch functions), which implicitly assume homogeneous dynamics...
February 2018: Journal of Applied Crystallography
Ti-Yen Lan, Jennifer L Wierman, Mark W Tate, Hugh T Philipp, Veit Elser, Sol M Gruner
[This corrects the article DOI: 10.1107/S1600576717006537.].
February 1, 2018: Journal of Applied Crystallography
Natalie T Johnson, Holger Ott, Michael R Probert
The rigorous analysis of crystallographic models, refined through the use of least-squares minimization, is founded on the expectation that the data provided have a normal distribution of residuals. Processed single-crystal diffraction data rarely exhibit this feature without a weighting scheme being applied. These schemes are designed to reflect the precision and accuracy of the measurement of observed reflection intensities. While many programs have the ability to calculate optimal parameters for applied weighting schemes, there are still programs that do not contain this functionality, particularly when moving beyond the spherical atom model...
February 1, 2018: Journal of Applied Crystallography
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