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Title: SINGLE CRYSTAL NEUTRON DIFFRACTION.

Abstract

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; formore » 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.« less

Authors:
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (US)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
777867
Report Number(s):
BNL-68112; KC030201
R&D Project: CO09; KC030201; TRN: AH200118%%508
DOE Contract Number:
AC02-98CH10886
Resource Type:
Book
Resource Relation:
Other Information: PBD: 13 Mar 2001
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BRAGG REFLECTION; CRYSTAL STRUCTURE; DIFFRACTION; MAGNETIC MOMENTS; MONOCRYSTALS; NEUTRON DIFFRACTION; NEUTRONS; SPACE GROUPS; THERMAL NEUTRONS

Citation Formats

KOETZLE,T.F. SINGLE CRYSTAL NEUTRON DIFFRACTION.. United States: N. p., 2001. Web.
KOETZLE,T.F. SINGLE CRYSTAL NEUTRON DIFFRACTION.. United States.
KOETZLE,T.F. Tue . "SINGLE CRYSTAL NEUTRON DIFFRACTION.". United States. doi:. https://www.osti.gov/servlets/purl/777867.
@article{osti_777867,
title = {SINGLE CRYSTAL NEUTRON DIFFRACTION.},
author = {KOETZLE,T.F.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 13 00:00:00 EST 2001},
month = {Tue Mar 13 00:00:00 EST 2001}
}

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  • 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 repeatsmore » 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.« less
  • The adsorption and desorption of hydrogen on clean and ordered single-crystal platinum(100), (110), and (111) and polycrystalline surfaces, well-characterized by LEED and Auger electron spectroscopy, were studied by a linear sweep voltammetry technique with sweep potentials of 0-0.4 v which are not anodic enough to result in oxidation and surface reconstruction. A single strong adsorption peak at 0.25 v was obtained for Pt(100) surface while both the (111) and (110) surface showed minor adsorption. A polycrystalline Pt electrode also showed one major strong peak and some minor features. Interpretation was based on the localized bond concept; crystallographic orientation is themore » major factor governing hydrogen adsorption on platinum electrode surfaces, but potential cycling undoubtedly modifies the surface structure and thus the adsorptive properties.« less
  • This lecture reviews the main concepts, applications and capabilities of different non-conventional approaches to single-crystal x-ray diffraction (SXD) experiment utilizing synchrotron radiation for applications in high-pressure research. You will learn how such experiment can be designed and performed to best answer the scientific goals of your study and, at the same time overcome the main technical limitations imposed by the high-pressure device and type of measurement. The emphasis will be placed on experiments that cannot be performed using laboratory instruments, e.g. involving ultrahigh (>50 GPa) pressures, poor quality samples, laser heating in diamond anvil cell (DAC), etc. The main goalmore » of the presentation is to convince you that even if you are not an expert crystallographer, with good understanding of the general basic principles of synchrotron SXD experiments in a DAC you can successfully use these techniques as valuable and easy tools in your own high-pressure research.« less
  • High-purity tantalum single crystal cylinders oriented with [011] parallel to the cylinder axis were deformed 10, 20, and 30 percent in compression. The engineering stress-strain curve exhibited an up-turn at strains greater than {approximately}20% while the samples took on an ellipsoidal shape during testing, elongated along the [100] direction with almost no dimensional change along [0{bar 1}1]. Two orthogonal planes were selected for characterization using Orientation Imaging Microscopy (OIM): one plane containing [100] and [011] (longitudinal) and the other in the plane containing [0{bar 1}1] and [011] (transverse). OIM revealed patterns of alternating crystal rotations that develop as a functionmore » of strain and exhibit evolving length scales. The spacing and magnitude of these alternating misorientations increases in number density and decreases in spacing with increasing strain. Classical crystal plasticity calculations were performed to simulate the effects of compression deformation with and without the presence of friction. The calculated stress-strain response, local lattice reorientations, and specimen shape are compared with experiment.« less
  • To elucidate the phase change and volume variation of SOFC cathode materials, La{sub 1{minus}y}MnO{sub 3+d} (y = 0, 0.05) and La{sub 1{minus}x}Sr{sub x}MnO{sub 3+d}, with temperature and oxygen nonstoichiometry, high temperature X-ray diffraction analysis was made in the atmosphere of the controlled oxygen partial pressure. The structure above 800 C was found to be rhombohedral R{bar 3}C for the composition with x = 0 and 0.1, irrespective of the oxygen content. Both the lattice volume and thermal expansion coefficient increase with decreasing the oxygen content. For x{>=}0.3, the structure above 800 C was essentially cubic. The variation in the latticemore » parameter with P(O{sub 2}) at P(O{sub 2}) > 10{sup {minus}4} atm became smaller with the increase in Sr content, x, due to the smaller oxygen excess nonstoichiometry for the larger x in La{sub 1{minus}x}Sr{sub x}MnO{sub 3+d}.« less