Performance of a multi-wavelength monochromator system for neutron single-crystal and powder diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 291-295 ◽  
Author(s):  
F. U. Ahmed ◽  
I. Tanaka ◽  
N. Niimura
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Collection Efficiency ◽  
Neutron Imaging ◽  
Imaging Plate ◽  
Multiple Reflections ◽  
Multi Wavelength ◽  
Sample Position ◽  
Diffraction Patterns ◽  
Point Detector

In order to improve significantly data collection efficiency, the advantages of using multi-wavelengths in single-crystal neutron diffraction as well as in powder neutron diffraction were established by experiments using a stacked monochromator assembly of two elastically bent perfect Si(111) and Si(220) crystals. The TAS-2 spectrometer on JRR-3M at JAERI (Japan Atomic Energy Research Institute) was employed for these experiments. Each crystal was elastically bent in order to increase the flux density at the sample position. Two wavelengths, λ1= 1.80 Å for Si(220) and λ2= 2.94 Å for Si(111), were selected. The alignment of the stacked monochromator was successful and a well defined rocking curve of approximately 0.3° full width at half-maximum (FWHM) was obtained. Diffraction patterns of Si powder were collected using the TAS-2 point detector as well as a neutron imaging plate (NIP) detector to compare the relative performance of the two detector systems. With the NIP detector, it was possible to acquire multiple reflections simultaneously with better intensity, better statistics and higher spatial resolution with an open geometry. The NIP detector was used to obtain the diffraction pattern of a single crystal of the organic compound piperidine cobaloxime. For the systems investigated in this study, it was possible to assign unambiguously rings or spots to diffraction by λ1or by λ2in the case of powder and single-crystal diffraction.

Quantitative estimation of electron beam irradiation damage of polyethylene single crystal using imaging plate

1992 ◽  
Vol 50 (1) ◽  
pp. 382-383
Author(s):  
T. Oikawa ◽  
D. Shindo ◽  
J. Kudoh ◽  
S. Aita ◽  
M. Kersker
Keyword(s):  
Electron Beam ◽  
Single Crystal ◽  
Electron Beam Irradiation ◽  
Quantitative Estimation ◽  
Irradiation Damage ◽  
Imaging Plate ◽  
Beam Irradiation ◽  
Polyethylene Single Crystal ◽  
Diffraction Patterns ◽  
Intensity Fading

The degree of electron beam irradiation damage is estimated from the intensity fading of diffraction spots and the lattice spacing increase of the specimen. Previously, qualitative estimatin of the damage was made for beam-sensitive specimens, e.g., polymers and biomolecules. In the present study, the degree of irradiation damage was estimated by quantitative measurement of the intensity of electron diffraction patterns, using the Imaging Plate (IP). Polyethylene single crystal, which is a typical material for polymers, was used as a specimen.

Quantitative Electron Microscope with imaging plate

1994 ◽  
Vol 52 ◽  
pp. 408-409
Author(s):  
D. Shindo
Keyword(s):  
Electron Microscope ◽  
Dynamic Range ◽  
Processing System ◽  
Digital Data ◽  
Imaging Plate ◽  
Crystal Thickness ◽  
X Ray Diffraction ◽  
Resolution Electron ◽  
Electron Intensity ◽  
Diffraction Patterns

Imaging plate has good properties, i.e., a wide dynamic range and good linearity for the electron intensity. Thus the digital data (2048x1536 pixels, 4096 gray levels in log scale) obtained with the imaging plate can be used for quantification in electron microscopy. By using the image processing system (PIXsysTEM) combined with a main frame (ACOS3900), quantitative analysis of electron diffraction patterns and high-resolution electron microscope (HREM) images has been successfully carried out.In the analysis of HREM images observed with the imaging plate, quantitative comparison between observed intensity and calculated intensity can be carried out by taking into account the experimental parameters such as crystal thickness and defocus value. An example of HREM images of quenched Tl2Ba2Cu1Oy (Tc = 70K) observed with the imaging plate is shown in Figs. 1(b) - (d) comparing with a structure model proposed by x-ray diffraction study of Fig. 1 (a). The image was observed with a JEM-4000EX electron microscope (Cs =1.0 mm).

SINGLE CRYSTAL NEUTRON DIFFRACTION STUDIES OF HCP RARE EARTH THORIUM ALLOYS

1971 ◽  
Vol 32 (C1) ◽  
pp. C1-1128-C1-1129
Author(s):  
H. R. CHILD ◽  
W. C. KOEHLER
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Single Crystal

NEUTRON DIFFRACTION AND MAGNETIZATION STUDY OF THE MAGNETIC PHASE DIAGRAM OF UAs0.75Se0.25 SINGLE CRYSTAL

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-479-C8-480 ◽  
Author(s):  
M. Kuznietz ◽  
P. Burlet ◽  
J. Rossat-Mignod ◽  
O. Vogt ◽  
K. Mattenberger ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Magnetization Study

Single crystal neutron diffraction studies of antiferromagnets at low temperatures in applied magnetic fields

1959 ◽  
Vol 20 (2-3) ◽  
pp. 180-184 ◽  
Author(s):  
W.C. Koehler ◽  
M. K. Wilkinson ◽  
J.W. Cable ◽  
E.O. Wollan
Keyword(s):  
Magnetic Fields ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Low Temperatures

Water Molecule Dispositions in the Cesium Sulfate α- and β-Alums: Single-Crystal Neutron Diffraction Studies of CsM(SO4)2.12H2O (M=V, Rh)

1993 ◽  
Vol 46 (9) ◽  
pp. 1337 ◽  
Author(s):  
JK Beattie ◽  
SP Best ◽  
FH Moore ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Neutron Diffraction ◽  
Water Molecule ◽  
Single Crystal ◽  
Tilt Angle ◽  
Room Temperature ◽  
Bond Angle ◽  
Sulfate Salt ◽  
Cell Dimensions ◽  
Coordinated Water ◽  
Unit Cell Dimensions

Room-temperature single-crystal neutron diffraction studies are recorded for two alums, Cs( Rh /V)(SO4)2.12H2O [cubic, Pa3, a 12.357(5) ( Rh ), 12.434(1)Ǻ (V)], residuals 0.037 and 0.068 for 328 and 164 'observed' reflections, with the intention of defining water molecule hydrogen atom orientations. Whereas the two tervalent hexaaqua cations are similar in size [ rM -O = 2.010(6)Ǻ (M = V) and 2.006(2)Ǻ (M = Rh )] the vanadium salt adopts the β alum modification while rhodium gives an α alum. Significantly, the water coordination geometry is different in the two cases with the tilt angle between the plane of the water molecule and the M-O bond vector being 1° (M = V) and 35° (M = Rh ). The tilt angle for water coordinated to rhodium in CsRh (SeO4)2.12H2O is inferred from the unit cell dimensions to be similar to that of the corresponding sulfate salt and not that which generally pertains for caesium selenate alums. Significant differences in the H-O-H bond angle are found for trigonal planar and trigonal pyramidal water coordination, suggesting that differences in the metal(III)-water interaction are a determinant of the geometry of the coordinated water molecule in the caesium sulfate/ selenate alum lattices.

scholarly journals H-bonding in lazulite: a single-crystal neutron diffraction study at 298 and 3 K

2018 ◽  
Vol 46 (5) ◽  
pp. 449-458
Author(s):  
G. Diego Gatta ◽  
Pietro Vignola ◽  
Nicola Rotiroti ◽  
Martin Meven
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Study ◽  
Neutron Diffraction Study

Use of Neutron Diffraction for Describing Texture of Isostatically-Pressed Molybdite Powders

2005 ◽  
Vol 105 ◽  
pp. 83-88 ◽  
Author(s):  
H. Sitepu ◽  
Heinz Günter Brokmeier
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Quantitative Description ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data ◽  
Pole Figures ◽  
Diffraction Patterns ◽  
Excellent Tool

The modelling and/or describing of texture (i.e. preferred crystallographic orientation (PO)) is of critical importance in powder diffraction analysis - for structural study and phase composition. In the present study, the GSAS Rietveld refinement with generalized spherical harmonic (GSH) was used for describing isostatically-pressed molybdite powders neutron powder diffraction data collected in the ILL D1A instrument. The results showed that for texture in a single ND data of molybdite the reasonable crystal structure parameters may be obtained when applying corrections to intensities using the GSH description. Furthermore, the WIMV method was used to extract the texture description directly from a simultaneous refinement with 1368 whole neutron diffraction patterns taken from the sample held in a variety of orientations in the ILL D1B texture goniometer. The results provided a quantitative description of the texture refined simultaneously with the crystal structure. Finally, the (002) molybdite pole-figures were measured using the GKSS TEX2 texture goniometer. The results showed that neutron diffraction is an excellent tool to investigate the texture in molybdite.

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