Real-space refinement of single-crystal electron diffuse scattering and its application to Bi2Ru2O7−δ

2007 ◽  
Vol 19 (33) ◽  
pp. 335216 ◽  
Author(s):  
A L Goodwin ◽  
R L Withers ◽  
H-B Nguyen
Keyword(s):  
Single Crystal ◽  
Diffuse Scattering ◽  
Real Space ◽  
Crystal Electron

Influence of magnetism on chemical order in a FeAl19.5at single crystal. High temperature measurements of neutron diffuse scattering

1991 ◽  
Vol 1 (2) ◽  
pp. 247-260 ◽  
Author(s):  
V. Pierron-Bohnes ◽  
M. C. Cadeville ◽  
A. Finel ◽  
O. Schaerpf
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Diffuse Scattering ◽  
Temperature Measurements ◽  
Chemical Order ◽  
High Temperature Measurements

Challenging structure determination from powder diffraction data: two pharmaceutical salts and one cocrystal with Z′ = 2

2019 ◽  
Vol 234 (4) ◽  
pp. 257-268 ◽  
Author(s):  
Carina Schlesinger ◽  
Michael Bolte ◽  
Martin U. Schmidt
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Real Space ◽  
Powder Diffraction Data ◽  
The Real ◽  
Pharmaceutical Salts ◽  
Structure Solution ◽  
Space Method

Abstract Structure solution of molecular crystals from powder diffraction data by real-space methods becomes challenging when the total number of degrees of freedom (DoF) for molecular position, orientation and intramolecular torsions exceeds a value of 20. Here we describe the structure determination from powder diffraction data of three pharmaceutical salts or cocrystals, each with four molecules per asymmetric unit on general position: Lamivudine camphorsulfonate (1, P 21, Z=4, Z′=2; 31 DoF), Theophylline benzamide (2, P 41, Z=8, Z′=2; 23 DoF) and Aminoglutethimide camphorsulfonate hemihydrate [3, P 21, Z=4, Z′=2; 31 DoF (if the H2O molecule is ignored)]. In the salts 1 and 3 the cations and anions have two intramolecular DoF each. The molecules in the cocrystal 2 are rigid. The structures of 1 and 2 could be solved without major problems by DASH using simulated annealing. For compound 3, indexing, space group determination and Pawley fit proceeded without problems, but the structure could not be solved by the real-space method, despite extensive trials. By chance, a single crystal of 3 was obtained and the structure was determined by single-crystal X-ray diffraction. A post-analysis revealed that the failure of the real-space method could neither be explained by common sources of error such as incorrect indexing, wrong space group, phase impurities, preferred orientation, spottiness or wrong assumptions on the molecular geometry or other user errors, nor by the real-space method itself. Finally, is turned out that the structure solution failed because of problems in the extraction of the integrated reflection intensities in the Pawley fit. With suitable extracted reflection intensities the structure of 3 could be determined in a routine way.

Analysis of Single-Crystal Neutron Diffuse Scattering from Ice Ih

1997 ◽  
Vol 101 (32) ◽  
pp. 6188-6191 ◽  
Author(s):  
M. N. Beverley ◽  
V. M. Nield
Keyword(s):  
Single Crystal ◽  
Diffuse Scattering

Short range order in a single crystal of Fe-19.5 at.% Al in the ferromagnetic range measured through X-ray diffuse scattering

1990 ◽  
Vol 38 (12) ◽  
pp. 2701-2710 ◽  
Author(s):  
V. Pierron-Bohnes ◽  
S. Lefebvre ◽  
M. Bessiere ◽  
A. Finel
Keyword(s):  
Single Crystal ◽  
Diffuse Scattering ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray

Analysis of diffuse scattering from the mineral mullite

1994 ◽  
Vol 27 (5) ◽  
pp. 742-754 ◽  
Author(s):  
B. D. Butler ◽  
T. R. Welberry
Keyword(s):  
Diffuse Scattering ◽  
Real Space ◽  
Order Parameters ◽  
Scattering Data ◽  
Local Order ◽  
Near Neighbour ◽  
Diffuse Intensity ◽  
Space Model ◽  
Least Squares Techniques ◽  
Space Volume

A full reciprocal-space volume of diffuse scattering data from a single-crystal of the mineral mullite, Al2(Al2 + 2x Si2 − 2x )O10 − x , x = 0.4, was collected. These data were analysed using least-squares techniques by writing an equation for the diffuse scattering that involves only the local order between vacancies on specific oxygen sites in the material. The effect of the large, but predictable, cation shifts on the diffuse intensity is taken account of in the coefficients of the oxygen-vacancy short-range-order intensities. This analysis shows that the vacancies are negatively correlated at the near-neighbour ½ 〈110〉, [110], 〈001〉 and 〈011〉 interatomic vectors and positively correlated along the 〈010〉, 〈101〉, ½ 〈112〉 and ½ 〈310〉 vectors. Subsequent Monte Carlo modelling of the structure based on these local-order parameters demonstrates that the structure of mullite is dominated by effective near-neighbour vacancy–vacancy repulsive interactions. A real-space model of mullite is presented that is approximately consistent with the measured local-order parameters.

Stereo analysis of single crystal electron diffraction data

1981 ◽  
Vol 6 (1) ◽  
pp. 227-235 ◽  
Author(s):  
P. Fraundorf
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Stereo Analysis ◽  
Crystal Electron
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