Artykuły w czasopismach: „Neutron diffraction”

1

Artioli, Gilberto. "Single-crystal neutron diffraction". European Journal of Mineralogy 14, nr 2 (22.03.2002): 233–39. http://dx.doi.org/10.1127/0935-1221/2002/0014-0233.

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Jorgensen, James D., i John M. Newsam. "Neutron Powder Diffraction". MRS Bulletin 15, nr 11 (listopad 1990): 49–55. http://dx.doi.org/10.1557/s088376940005836x.

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For many classes of materials, neutron diffraction is the best way to obtain detailed atomic-level structural information. Diffraction experiments on single crystals provide the most precise data, but sufficiently large specimens (>0.1–0.5 mm3) are often not available. Steady development of instrumentation and data analysis techniques, however, has now made it possible to obtain comparably precise structural information from neutron diffraction experiments on powder samples. Such studies have played a prominent role in solid state physics, chemistry, and materials science in recent years. The special capabilities that have contributed to the success of this technique include atomic cross sections that are often favorable for a particular structural problem, high neutron penetrating power, the excellent resolution achieved with state-of-the-art diffractometers, and steadily advancing analysis techniques that facilitate obtaining structural information from a diverse range of polycrystalline materials.As Axe, Pynn, and Hayter note in their introductory article in this issue of the MRS BULLETIN, atomic scattering cross sections for neutrons are not simply a function of atomic number, as is the case for x-rays. The scattering is predominantly from the nuclei (thus avoiding the form factor diminution observed for x-ray scattering), and coherent neutron scattering cross sections can, generally, be as large for light atoms as for heavy atoms. Light atoms, such as hydrogen (deuterium), oxygen, nitrogen, carbon, or lithium, can therefore be located in the presence of heavier atoms. This advantage has led to the widespread use of neutron powder diffraction for studing metal hydrides and, more recently, oxide superconductors.

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3

MEKATA, Mamoru. "Neutron Diffraction." RADIOISOTOPES 44, nr 4 (1995): 256–66. http://dx.doi.org/10.3769/radioisotopes.44.256.

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4

WU, XIANG-YAO, BAI-JUN ZHANG, XIAO-JING LIU, BING LIU, CHUN-LI ZHANG i JING-WU LI. "QUANTUM THEORY OF NEUTRON DIFFRACTION". International Journal of Modern Physics B 23, nr 15 (20.06.2009): 3255–64. http://dx.doi.org/10.1142/s0217979209052601.

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Phenomena of electron, neutron, atomic, and molecular diffraction have been studied in many experiments, and these experiments have been explained by some theoretical works. We study neutron single and double-slit diffraction with a new quantum mechanical approach. The calculation results are compared with the experimental data obtained with cold neutrons.

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5

Delapalme, A. "Use of Extinction Corrections in Neutron Diffraction Experiments". Australian Journal of Physics 41, nr 3 (1988): 383. http://dx.doi.org/10.1071/ph880383.

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The study of extinction by neutrons reveals many features of the extinction problem: theory and practical cases, polarised and unpolarised neutron cases. Special attention is given to the usual extinction corrections for neutron diffraction experiments, showing the relative importance of structure factor, wavelength, Lorentz factor, mosaic and the path of neutrons through the crystal. Two problems are reviewed: (a) how to detect the presence of extinction in both cases of a single crystal experiment with polarised and unpolarised neutrons; and (b) after experimental evidence for extinction in a neutron diffraction experiment, how to follow a reliable way to correct the neutron diffraction data in both cases of polarised and unpolarised neutron experiments. Some examples are given.

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6

Brokmeier, H. G. "Neutron Diffraction Texture Analysis of Multi-Phase Systems". Textures and Microstructures 10, nr 4 (1.01.1989): 325–46. http://dx.doi.org/10.1155/tsm.10.325.

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Neutron diffraction methods for texture analysis are closely parallel to well-known X-ray diffraction techniques. The chief advantage of neutron diffraction over X-ray diffraction, however, arises from the fact that the interaction of neutrons with matter is relatively weak, and consequently the penetration depth of neutrons is 102–103 times larger than that of X-rays. Hence neutron diffraction is an efficient tool for measuring textures in multi-phase systems. Based on the high transmission of a neutron beam the effect of anisotropic absorption in multi-phase materials can be neglected in most cases. Moreover, the analysis of bulk textures becomes possible, such that textures in a wide variety of multi-phase systems can be studied which are of special interest in engineering and science (metals, alloys, composites, ceramics and geological specimens).

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7

Guthrie, Malcolm, Reinhard Boehler, Jamie Molaison, Karunakar Kothapalli, Antonio dos Santos i Christopher Tulk. "Neutron diffraction in diamond anvil cells". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C895. http://dx.doi.org/10.1107/s2053273314091049.

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Neutron diffraction provides many unique advantages for structural studies of materials under extremes of pressure. In addition to the famous sensitivity to light atom positions, neutrons are sensitive to long-range magnetic order and have an extremely high spatial resolution. However, a major downside of neutron techniques, that is keenly felt in high pressure studies, is the comparative weakness of available sources. Some of these limitations have been recently overcome at the Spallation Neutron Source, ORNL, using a newly developed supported diamond-anvil device. For the first time, this new capability allows the possibility of conducting neutron diffraction measurements at pressures approaching 100 GPa. These new developments will be discussed with a look towards the prospects for advances in neutron scattering at high pressure in the near future.

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8

KAMIYAMA, Takashi. "Neutron Powder Diffraction". Nihon Kessho Gakkaishi 46, nr 4 (2004): 259–67. http://dx.doi.org/10.5940/jcrsj.46.259.

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Ressouche, E. "Polarized neutron diffraction". École thématique de la Société Française de la Neutronique 13 (2014): 02002. http://dx.doi.org/10.1051/sfn/20141302002.

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Freund, Andreas K., Hao Qu, Xiang Liu, Mike Crosby i Changyong Chen. "Optimization of highly oriented pyrolytic graphite applied to neutron crystal optics". Journal of Applied Crystallography 55, nr 2 (16.02.2022): 247–57. http://dx.doi.org/10.1107/s1600576722000127.

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The neutron diffraction properties of highly oriented pyrolytic graphite (HOPG) are reviewed using experimental results that have been obtained by diffraction of high-energy gamma rays, X-rays and neutrons. The interpretation of the empirical data based on diffraction theory leads to generic diagrams that display the performance of HOPG as a function of crystal thickness, mosaic spread and neutron wavelength. The analysis of the relation between the defect structure and diffraction properties demonstrates the usefulness of a detailed X-ray diffraction study to maximize the efficiency of composite neutron monochromators and analyzers. The optimization procedure is illustrated by the configuration of a double-focusing monochromator.

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11

Pramanick, A., V. Lauter, X. L. Wang, K. An, H. Ambaye, R. J. Goyette Jr, J. Yi, Z. Gai i A. D. Stoica. "Polarized neutron diffraction at a spallation source for magnetic studies". Journal of Applied Crystallography 45, nr 5 (1.09.2012): 1024–29. http://dx.doi.org/10.1107/s0021889812034474.

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The availability of high-power spallation neutron sources, along with advances in the development of coupled moderators and neutron polarizers, has made it possible to use polarized neutrons on time-of-flight diffractometers forin situstudies of phenomena contributing to field-induced magnetization of a material. Different electronic and structural phenomena that contribute to the overall magnetization of a material can be studied and clearly identified with polarized neutron diffraction measurements. This article reports the first results from polarized neutron diffraction experiments on a time-of-flight instrument at a spallation source. Magnetic field-induced rotation of electron spins in an Ni–Mn–Ga single crystal was measured with polarized neutron diffraction at the MAGICS reflectometer at the Spallation Neutron Source at Oak Ridge National Laboratory. The difference in intensities measured with spin-up and spin-down polarized neutrons is proportional to the field-induced magnetization of the crystal. The polarized neutron measurements indicate that the magnetic form factor for the 3delectrons of Mn in Ni–Mn–Ga is lower than the value reported earlier for an ideal spherical symmetry of electronic distribution. Future experiments for studying field-induced magnetization in materials following the current methodology are outlined.

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12

Kudryavtsev, Yu V., A. E. Perekos, I. N. Glavatskyy, J. Dubowik i Yu B. Skirta. "Neutron Diffraction Study of Fe$_{2}$MnGa Heusler Alloys". METALLOFIZIKA I NOVEISHIE TEKHNOLOGII 38, nr 1 (23.03.2016): 53–66. http://dx.doi.org/10.15407/mfint.38.01.0053.

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13

Ståhl, Kenny, i Gilberto Artioli. "A neutron powder diffraction study of fully deuterated laumontite". European Journal of Mineralogy 5, nr 5 (1.01.1993): 851–56. http://dx.doi.org/10.1127/ejm/5/5/0851.

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Schäfer, Wolfgang. "Neutron diffraction applied to geological texture and stress analysis". European Journal of Mineralogy 14, nr 2 (22.03.2002): 263–89. http://dx.doi.org/10.1127/0935-1221/2002/0014-0263.

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15

Giustetto, Roberto, i Giacomo Chiari. "Crystal structure refinement of palygorskite from neutron powder diffraction". European Journal of Mineralogy 16, nr 3 (7.06.2004): 521–32. http://dx.doi.org/10.1127/0935-1221/2004/0016-0521.

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16

Tremsin, Anton S., Jason B. McPhate, John V. Vallerga, Oswald H. W. Siegmund, Winfried Kockelmann, Anna Paradowska, Shu Yan Zhang, Joe Kelleher, Axel Steuwer i W. Bruce Feller. "High-Resolution Strain Mapping Through Time-of-Flight Neutron Transmission Diffraction". Materials Science Forum 772 (listopad 2013): 9–13. http://dx.doi.org/10.4028/www.scientific.net/msf.772.9.

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The spatial resolution of time of flight neutron transmission diffraction was recently improved by the extension of photon/electron counting technology to imaging of thermal and cold neutrons. The development of novel neutron sensitive microchannel plates enables neutron counting with spatial resolution of ~55 um and time-of-flight accuracy of ~1 us, with efficiency as high as 70% for cold and ~40% for thermal neutrons. The combination of such a high resolution detector with a pulsed collimated neuron beam provides the opportunity to obtain a 2-dimensional map of neutron transmission spectra in one measurement. The results of our neuron transmission measurements demonstrate that maps of strains integrated along the beam propagation direction can be obtained with ~100 microstrain accuracy and spatial resolution of ~100 um providing there are sufficient neutron events collected. In this paper we describe the capabilities of the MCP neutron counting detectors and present the experimental results of 2-dimensional strain maps within austenitic steel compact tension (CT) crack samples measured at the ENGIN-X beamline of the ISIS pulsed neutron source.

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17

Feldmann, K. "Texture Investigations by Neutron Time-of-Flight Diffraction". Textures and Microstructures 10, nr 4 (1.01.1989): 309–23. http://dx.doi.org/10.1155/tsm.10.309.

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For the majority of isotopes the thermal neutron absorption cross section is two or more orders lower than that for X-rays. This makes neutron diffraction well-suited for bulk texture investigations. Some characteristics of neutron diffraction are discussed. The principles of neutron time-of-flight diffraction are described. The pole figure determination by means of TOF technique is considered. The main parameters of the present Dubna texture facility are given. Further developments of the experimental technique are considered. The application of the TOF technique for inverse pole figure measurement is discussed as an approach to direct observation of the texture forming process. The magnetic moments of neutrons can be used to study magnetic textures. Two different techniques are discussed.

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18

Wenk, H. R. "Neutron Diffraction Texture Analysis". Reviews in Mineralogy and Geochemistry 63, nr 1 (1.01.2006): 399–426. http://dx.doi.org/10.2138/rmg.2006.63.15.

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19

Nelmes, R. J., J. S. Loveday, C. L. Bull, M. Guthrie, K. Komatsu i H. E. Maynard. "Single crystal neutron diffraction". Acta Crystallographica Section A Foundations of Crystallography 63, a1 (22.08.2007): s215. http://dx.doi.org/10.1107/s0108767307095098.

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Langan *, Paul. "Neutron diffraction from fibers". Crystallography Reviews 11, nr 2 (kwiecień 2005): 125–47. http://dx.doi.org/10.1080/08893110500148960.

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Ankner, J. F., H. Zabel, D. A. Neumann i C. F. Majkrzak. "Grazing-angle neutron diffraction". Physical Review B 40, nr 1 (1.07.1989): 792–95. http://dx.doi.org/10.1103/physrevb.40.792.

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Fischer, Peter, Lukas Keller, JÜUrg Schefer i Joachim Kohlbrecher. "Neutron diffraction at SINQ". Neutron News 11, nr 3 (styczeń 2000): 19–21. http://dx.doi.org/10.1080/10448630008233743.

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23

Kargl, V., P. Böni, A. Mirmelstein, B. Roessli i D. Sheptyakov. "Magnetic neutron diffraction in". Physica B: Condensed Matter 359-361 (kwiecień 2005): 1255–57. http://dx.doi.org/10.1016/j.physb.2005.01.377.

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24

Martin, J. M., M. R. Lees, D. McK Paul, P. Dai, C. Ritter i Y. J. Bi. "Neutron-diffraction study ofCeCuGa3". Physical Review B 57, nr 13 (1.04.1998): 7419–22. http://dx.doi.org/10.1103/physrevb.57.7419.

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Robinson, D. S., J. L. Zarestky, C. Stassis i D. T. Peterson. "Neutron diffraction study ofScD1.8". Physical Review B 34, nr 10 (15.11.1986): 7374–75. http://dx.doi.org/10.1103/physrevb.34.7374.

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ANKNER, J. F., H. ZABEL, D. A. NEUMANN, C. F. MAJKRZAK, J. A. DURA i C. P. FLYNN. "GRAZING-ANGLE NEUTRON DIFFRACTION". Le Journal de Physique Colloques 50, nr C7 (październik 1989): C7–189—C7–197. http://dx.doi.org/10.1051/jphyscol:1989719.

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Mat’aš, S., I. Bat’ko, K. Flachbart, Y. Paderno, N. Shitsevalova i K. Siemensmeyer. "Neutron diffraction on HoB12". Journal of Magnetism and Magnetic Materials 272-276 (maj 2004): E435—E437. http://dx.doi.org/10.1016/j.jmmm.2003.11.362.

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Brokmeier, H. G. "Neutron diffraction texture analysis". Physica B: Condensed Matter 234-236 (czerwiec 1997): 977–79. http://dx.doi.org/10.1016/s0921-4526(96)01230-6.

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Caignaert, V., N. Nguyen i B. Raveau. "La2SrCu2O6: Neutron diffraction study". Materials Research Bulletin 25, nr 2 (luty 1990): 199–204. http://dx.doi.org/10.1016/0025-5408(90)90046-5.

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Tomy, C. V., L. J. Chang, D. McK. Paul, N. H. Andersen i M. Yethiraj. "Neutron diffraction from HoNi2b2C". Physica B: Condensed Matter 213-214 (sierpień 1995): 139–41. http://dx.doi.org/10.1016/0921-4526(95)00085-n.

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Burlet, P., J. Rossat-Mignod, S. vuevel, O. Vogt, J. C. Spirlet i J. Rebivant. "Neutron diffraction on actinides". Journal of the Less Common Metals 121 (lipiec 1986): 121–39. http://dx.doi.org/10.1016/0022-5088(86)90521-7.

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Ioffe, A. I. "Diffraction-grating neutron interferometers". Physica B+C 151, nr 1-2 (lipiec 1988): 50–56. http://dx.doi.org/10.1016/0378-4363(88)90144-1.

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Plumier, R., M. Sougi i J. L. Soubeyroux. "Neutron diffraction reinvestigation of". Journal of Alloys and Compounds 178, nr 1-2 (luty 1992): 51–56. http://dx.doi.org/10.1016/0925-8388(92)90246-6.

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Hubbard, Camden. "Neutron powder diffraction advances". Powder Diffraction 32, nr 4 (grudzień 2017): 221. http://dx.doi.org/10.1017/s0885715617001075.

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Goldman, A. I., S. M. Shapiro, D. E. Cox, J. L. Smith i Z. Fisk. "Neutron-diffraction studies ofUBe13andThBe13". Physical Review B 32, nr 9 (1.11.1985): 6042–44. http://dx.doi.org/10.1103/physrevb.32.6042.

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Toliński, T., A. Szytuła, A. Hoser, A. Kowalczyk i B. Andrzejewski. "Neutron diffraction on TmNi4Al". physica status solidi (b) 243, nr 15 (grudzień 2006): 4064–69. http://dx.doi.org/10.1002/pssb.200642049.

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Chandler, GS, D. Jayatilaka i SK Wolff. "Electronic Structure from Polarised Neutron Diffraction". Australian Journal of Physics 49, nr 2 (1996): 261. http://dx.doi.org/10.1071/ph960261.

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The polarised neutron diffraction experiment is described and the nature of the information obtained is outlined. In many cases interpretation of the experiment assumes that the crystal is made up of non-interacting molecular or ionic units. The soundness of this assumption is examined in the case of copper Tutton salt. Polarised neutrons are scattered by the crystal magnetisation density which has a contribution from the orbital motion of electrons. A method for including the spin-orbit contribution to this effect is described for the particular example of the CoCI24− ion.

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38

Liebschner, Dorothee, Pavel V. Afonine, Nigel W. Moriarty, Paul Langan i Paul D. Adams. "Evaluation of models determined by neutron diffraction and proposed improvements to their validation and deposition". Acta Crystallographica Section D Structural Biology 74, nr 8 (24.07.2018): 800–813. http://dx.doi.org/10.1107/s2059798318004588.

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The Protein Data Bank (PDB) contains a growing number of models that have been determined using neutron diffraction or a hybrid method that combines X-ray and neutron diffraction. The advantage of neutron diffraction experiments is that the positions of all atoms can be determined, including H atoms, which are hardly detectable by X-ray diffraction. This allows the determination of protonation states and the assignment of H atoms to water molecules. Because neutrons are scattered differently by hydrogen and its isotope deuterium, neutron diffraction in combination with H/D exchange can provide information on accessibility, dynamics and chemical lability. In this study, the deposited data, models and model-to-data fit for all PDB entries that used neutron diffraction as the source of experimental data have been analysed. In many cases, the reported R work and R free values were not reproducible. In such cases, the model and data files were analysed to identify the reasons for this mismatch. The issues responsible for the discrepancies are summarized and explained. The analysis unveiled limitations to the annotation, deposition and validation of models and data, and a lack of community-wide accepted standards for the description of neutron models and data, as well as deficiencies in current model refinement tools. Most of the issues identified concern the handling of H atoms. Since the primary use of neutron macromolecular crystallography is to locate and directly visualize H atoms, it is important to address these issues, so that the deposited neutron models allow the retrieval of the maximum amount of information with the smallest effort of manual intervention. A path forward to improving the annotation, validation and deposition of neutron models and hybrid X-ray and neutron models is suggested.

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Yasue, Ayumu, Mayu Kawakami, Kensuke Kobayashi, Junho Kim, Yuji Miyazu, Yuhei Nishio, Tomohisa Mukai, Satoshi Morooka i Manabu Kanematsu. "Accuracy of Measuring Rebar Strain in Concrete Using a Diffractometer for Residual Stress Analysis". Quantum Beam Science 7, nr 2 (10.05.2023): 15. http://dx.doi.org/10.3390/qubs7020015.

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Neutron diffraction is a noncontact method that can measure the rebar strain inside concrete. In this method, rebar strain and stress are calculated using the diffraction profile of neutrons irradiated during a specific time period. In general, measurement accuracy improves with the length of the measurement time. However, in previous studies, the measurement time was determined empirically, which makes the accuracy and reliability of the measurement results unclear. In this study, the relationship between the measurement time and the measurement standard deviation was examined for reinforced concrete specimens under different conditions. The aim was to clarify the accuracy of the measurement of rebar stress using the neutron diffraction method. It was found that if the optical setup of the neutron diffractometer and the conditions of the specimen are the same, there is a unique relationship between the diffraction intensity and the rebar stress standard deviation. Furthermore, using this unique relationship, this paper proposes a method for determining the measurement time from the allowable accuracy of the rebar stress, which ensures the accuracy of the neutron diffraction method.

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Rogante, M. "Inside welds: advanced characterization of residual stresses by neutron diffraction". Avtomatičeskaâ svarka (Kiev) 2020, nr 11 (28.11.2020): 20–26. http://dx.doi.org/10.37434/as2020.11.04.

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Rogante, M. "Inside welds: advanced characterization of residual stresses by neutron diffraction". Paton Welding Journal 2020, nr 11 (28.11.2020): 18–24. http://dx.doi.org/10.37434/tpwj2020.11.04.

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Rogante, M. "Inside welds: advanced characterization of residual stresses by neutron diffraction". Avtomatičeskaâ svarka (Kiev) 2020, nr 11 (28.11.2020): 20–26. http://dx.doi.org/10.37434/as2020.11.04.

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Rogante, M. "Inside welds: advanced characterization of residual stresses by neutron diffraction". Paton Welding Journal 2020, nr 11 (28.11.2020): 18–24. http://dx.doi.org/10.37434/tpwj2020.11.04.

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Paradowska, A. M., A. Tremsin, J. F. Kelleher, S. Y. Zhang, S. Paddea, G. Burca, J. A. James i in. "OS04F125 Modern and Historical Engineering Concerns Investigated by Neutron Diffraction". Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2011.10 (2011): _OS04F125——_OS04F125—. http://dx.doi.org/10.1299/jsmeatem.2011.10._os04f125-.

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45

Gibson, W. M., A. J. Schultz, H. H. Chen-Mayer, D. F. R. Mildner, T. Gnäupel-Herold, M. E. Miller, H. J. Prask, R. Vitt, R. Youngman i J. M. Carpenter. "Polycapillary focusing optic for small-sample neutron crystallography". Journal of Applied Crystallography 35, nr 6 (13.11.2002): 677–83. http://dx.doi.org/10.1107/s0021889802014917.

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The relatively low flux from neutron sources means that structural analysis using neutron diffraction requires large crystals that are often not available. The feasibility of a polycapillary focusing optic to produce a small intense spot of size < ∼0.5 mm for small crystals has been explored and such an optic has been tested both on a monochromatic and on a polychromatic beam. In a diffraction measurement from an α-quartz crystal using a 2.1° convergent beam from a pulsed neutron source, six diffraction peaks in the 1.5–4 Å wavelength bandwidth transmitted by the optic were observed. These diffraction spots show an intensity gain of 5.8 ± 0.9 compared with a direct beam diffracting from the same sample volume as that illuminated by the convergent beam.

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46

Willis, BTM. "Measurement of Thermal Diffuse Scattering Using Pulsed Neutron Diffraction". Australian Journal of Physics 41, nr 3 (1988): 477. http://dx.doi.org/10.1071/ph880477.

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Collective excitations in crystals can be examined with neutrons by means of the so-called 'diffraction method', without carrying out an energy analysis of the inelastically scattered neutrons. For studying thermal diffuse scattering (I'DS) from acoustic phonons, it is particularly advantageous to employ a white source of pulsed neutrons instead of a monochromatic source of reactor neutrons. Provided that the neutron velocity is less than the sound velocity in the crystal, each reciprocal-lattice point observed in backscattering Laue geometry is associated with a wavelength window within which TDS is forbidden. The edges of the window are readily measured to give the sound velocity as a function of the direction of propagation.

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Matthies, S., L. Lutteroti i H. R. Wenk. "Advances in Texture Analysis from Diffraction Spectra". Journal of Applied Crystallography 30, nr 1 (1.02.1997): 31–42. http://dx.doi.org/10.1107/s0021889896006851.

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The orientation distribution of a textured polycrystal has been traditionally determined from a few individual pole figures of lattice planes hkl, measured by X-ray or neutron diffraction. A new method is demonstrated that uses the whole diffraction spectrum, rather than extracted peak intensities, by combining ODF calculation with Rietveld crystal structure refinement. With this method, which is illustrated for a synthetic calcite texture, it is possible to obtain quantitative texture information from highly incomplete pole figures and regions of the diffraction spectrum with many overlapping peaks. The approach promises to be advantageous for low-symmetry compounds and composites with complicated diffraction spectra. The method is particularly elegant for time-of-flight neutron diffraction, saving beam time by using small pole-figure regions and many diffractions.

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48

Yu, Dunji, Yan Chen, David Conner, Kevin Berry, Harley Skorpenske i Ke An. "Effect of Collimation on Diffraction Signal-to-Background Ratios at a Neutron Diffractometer". Quantum Beam Science 8, nr 2 (30.05.2024): 14. http://dx.doi.org/10.3390/qubs8020014.

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High diffraction signal-to-background ratios (SBRs), the ratio of diffraction peak integrated intensity over its background intensity, are desirable for a neutron diffractometer to acquire good statistics for diffraction pattern measurements and subsequent data analysis. For a given detector, while the diffraction peak signals primarily depend on the characteristics of the neutron beam and sample coherent scattering, the background largely originates from the sample incoherent scattering and the scattering from the instrument space. In this work, we investigated the effect of collimation on neutron diffraction SBRs of Si powder measurements using one high-angle area detector bank coupled with six different collimation configurations in a large and complex instrument space at the engineering materials diffractometer VULCAN, SNS, ORNL. The results revealed that the diffraction SBRs can be significantly improved by a proper coarse collimator that leaves no gap between the detector and the collimator, and the improvement of SBRs by a fine radial collimator was remarkable with a proper coarse collimator in place but not distinguishable without one. It was also found that the diffraction SBRs were not effectively improved by adding the neutron-absorbing element boron to the fine radial collimator body, which indicates that either the absorption of secondary scattered neutrons by the added boron is insignificant or the collimator base material (resin and ABS) alone attenuates background scattering sufficiently. These findings could serve as a useful reference for diffractometer developers and/or operators to optimize their collimation to achieve higher diffraction SBRs.

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KAWASAKI, Takuro. "5th Year in Neutron Diffraction". Nihon Kessho Gakkaishi 56, nr 2 (2014): 139–40. http://dx.doi.org/10.5940/jcrsj.56.139.

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Radaelli, Paolo G., i James D. Jorgensen. "Neutron Diffraction from Novel Materials". MRS Bulletin 24, nr 12 (grudzień 1999): 24–28. http://dx.doi.org/10.1557/s0883769400053689.

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The discovery and development of new materials is the foundation of the science and technology “food chains.” Examples of new materials with novel properties that have stimulated new scientific questions and/or led to new technologies include liquid crystals, advanced batteries, structural ceramics, dielectrics, ferroelectrics, catalysts, high-temperature superconductors, har dmagnets, and magnetoresistive devices. Establishing the crystal structure of a newly discovered Compound is a mandatory first step, but the most important contribution of diffraction techniques is to provide an understanding of the relationships among chemical composition, crystal structure, and physical behavior. In this way, diffraction experiments provide critical Information for testing theories that explain novel behavior and guide the optimization of new materials to meet the demands of emerging technologies.The first samples of newly discovered materials are often polycrystalline. With state-of-the-art neutron powder diffraction data and Rietveld refinement techniques, for structures of modest complexity, the precision for atom positions rivals that obtained by single-crystal diffraction. Rietveld refinement is a method of obtaining accurate values for atom positions and other structural parameters from powder diffraction data by least-squares fitting of a calculated model to the full diffraction pattern. As evidence of thi s success, the Inorganic Crystal Structure Database contains 6044 entries from neutron powder diffraction, 7096 from laboratory x-ray powder diffraction, an d 228 from Synchrotron x-ray powder diffraction. Other reasons for the rapidly growing impact of neutron diffraction include the favorable neutron-scattering cross sections for light elements, the sensitivity to magnetic moments, and the ability to penetrate special sample environments for in situ studies. These strengths are widely accepted and have been exploited for many years. Previous reviews have focused on these topics.

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