scholarly journals Quantitative Analysis of Hydrogen Site and Occupancy in a Deep-Earth Hydrous Mineral by Time-of-Flight Single Crystal Laue Neutron Diffraction

2017 ◽  
Vol 59 (6) ◽  
pp. 309-315
Author(s):  
Takuo OKUCHI ◽  
Narangoo PUREVJAV ◽  
Naotaka TOMIOKA
Keyword(s):  
Quantitative Analysis ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Time Of Flight ◽  
Hydrous Mineral ◽  
Deep Earth

Quantitative analysis of the fibre texture of zirconium by time-of-flight neutron diffraction

1981 ◽  
Vol 16 (10) ◽  
pp. 1165-1172 ◽  
Author(s):  
K. Feldmann ◽  
M. Betzl ◽  
K. Walther ◽  
W. Matz
Keyword(s):  
Quantitative Analysis ◽  
Neutron Diffraction ◽  
Time Of Flight ◽  
Fibre Texture

Single Crystal Time-of-Flight Neutron Diffraction

2002 ◽  
Vol 85 (4) ◽  
pp. 297-318 ◽  
Author(s):  
J. Peters ◽  
W. Jauch
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Three Dimensional ◽  
Time Of Flight ◽  
Diffraction Method ◽  
Neutron Sources ◽  
X Ray ◽  
Sorting Technique ◽  
History Of ◽  
Neutron Diffraction Method

The last century has seen a large development in diffraction techniques. The time-of-flight neutron diffraction method is now so advanced that it provides high precision results for position and thermal parameters, which are complementary to other diffraction results from X-ray sources. Here we review the history of neutron sources, the difficulties encountered with the time-of-flight technique and an outlook for applications. In this context, we will show the limitations of existing neutron sources and the expected advantages of new spallation neutron sources. An overview of all corrections to be taken into account with the wavelength-sorting technique will be presented as well as actual results, how to overcome such problems, and the special difficulty of integration of three-dimensional Bragg peaks.

scholarly journals Application of Charge & Band-flipping to Time-of-Flight Neutron Diffraction Data

2014 ◽  
Vol 70 (a1) ◽  
pp. C188-C188 ◽  
Author(s):  
Pamela Whitfield ◽  
Alan Coehlo ◽  
Ashfia Huq ◽  
Christina Hoffmann ◽  
Xiaoping Wang
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Time Of Flight ◽  
Easy Access ◽  
Neutron Diffraction Data ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
Neutron Data

Charge-flipping has become a popular approach to ab-initio structure solution from X-ray powder diffraction data in particular due to its speed and need for minimal input other than lattice parameters. Given the appetite of charge-flipping for low d-spacing reflections, time-of-flight (TOF) neutron data should be a good match from a resolution standpoint, with easy access to high Q and lack of form-factor drop-off. One obvious issue with neutron data is the presence of elements with negative scattering lengths, where the inherent assumption of atoms always having positive `density' in the algorithm breaks down. This means that portions of the structure can be effectively invisible. Given that some of these elements (e.g. H and Mn) are commonly found in samples of interest the issue is more than simple academic curiosity. Of course such atoms can be found by difference maps, but the issue has also been addressed within the charge-flipping algorithm with the `band-flipping' modification [1]. Although Oszlányi & Sütö demonstrated the approach was viable with simulated neutron single crystal data [1], to the authors' knowledge it hasn't been used previously with experimental single crystal or powder neutron diffraction data. Powder diffraction data from POWGEN and wavelength-resolved TOF Laue single crystal data from TOPAZ at the Spallation Neutron Source have been used to probe the relative ease of charge-flipping with different TOF data using the TOPAS software package [2]. In addition the effectiveness of different customized band-flipping approaches has been tested to extract positions for positive and negative scattering elements simultaneously.

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