scholarly journals Directional pair distribution function for diffraction line profile analysis of atomistic models

2013 ◽  
Vol 46 (1) ◽  
pp. 63-75 ◽  
Author(s):  
Alberto Leonardi ◽  
Matteo Leoni ◽  
Paolo Scardi
Keyword(s):  
Distribution Function ◽  
Line Profile ◽  
Pair Distribution Function ◽  
Profile Analysis ◽  
Atomic Displacement ◽  
Strain Effect ◽  
Line Profile Analysis ◽  
Line Broadening ◽  
Diffraction Line Profile ◽  
Atomistic Models

The concept of the directional pair distribution function is proposed to describe line broadening effects in powder patterns calculated from atomistic models of nano-polycrystalline microstructures. The approach provides at the same time a description of the size effect for domains of any shape and a detailed explanation of the strain effect caused by the local atomic displacement. The latter is discussed in terms of different strain types, also accounting for strain field anisotropy and grain boundary effects. The results can in addition be directly read in terms of traditional line profile analysis, such as that based on the Warren–Averbach method.

Peak Profile Evaluation for Thin Films

2014 ◽  
pp. 212-241
Keyword(s):  
Thin Films ◽  
Crystallite Size ◽  
Line Profile ◽  
Interference Effect ◽  
Profile Analysis ◽  
Reciprocal Lattice ◽  
Partial Coherence ◽  
Line Profile Analysis ◽  
Line Broadening ◽  
Diffraction Line Profile

The special phenomena in X-ray diffraction line profile analysis occurring in thin films is overviewed in this chapter. In the case of textured nanocrystalline thin films, the line broadening caused by the crystallite size increases with the length of the diffraction vector. This effect is explained by the interference of X-rays scattered coherently from adjacent crystallites with close orientations. The partial coherence of adjacent nanocrystallites is caused by the overlapping of their reciprocal lattice points. The smaller the size and the stronger the orientation preference of crystallites, the better the coherence. This interference effect yields narrowing of line profiles at small diffraction angles, while it has no influence on line broadening at large angles. Therefore, the traditional line profile evaluation methods give much larger crystallite size than the real value and may detect a false microstrain broadening. Some ways for the correction of the interference effect are proposed. Detailed case studies are given for the determination of the defect structure in thin films by line profile analysis.

The Microstructure of Nanocrystalline Powders from Line Profile Analysis

2004 ◽  
Vol 443-444 ◽  
pp. 71-76 ◽  
Author(s):  
Nathalie Audebrand ◽  
Daniel Louër
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Theoretical Background ◽  
Nanocrystalline Powders ◽  
Line Profile Analysis ◽  
Line Broadening ◽  
Experimental Conditions ◽  
Profile Fitting ◽  
Propagation Of Errors ◽  
Structure Imperfection

The theoretical background currently used in line profile analysis is reviewed. It covers the size and structure imperfection effects at the origin of diffraction line broadening. The propagation of errors, i.e. old errors and new errors related to profile fitting techniques, is commented. The experimental conditions for minimising errors are described. Representative examples of microstructure characterisation of nanopowders are presented.

Defect Structures in Neutron Irradiated 6H-SiC Studied by X-Ray Diffraction Line Profile Analysis

2000 ◽  
Vol 640 ◽  
Author(s):  
C. Seitz ◽  
A. Magerl ◽  
R. Hock ◽  
H. Heissenstein ◽  
R. Helbig
Keyword(s):  
Line Profile ◽  
Correlation Length ◽  
Defect Structure ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Temperatures ◽  
Diffraction Line Profile

ABSTRACTWe have investigated by x-ray diffraction defect structures in 6H-SiC after neutron irradiation with different fluences and followed by different annealing procedures. An interpretation along a model of Klimanek [1, 4–6] shows, that higher fluences lead to a stronger than linear reduction of the correlation length, whereas higher annealing temperatures correlate with a better recovery of the correlation length. In addition defects of 1st kind created by irradiation are reduced by annealing. We find that annealing changes the character of the defects and it accentuates a defect structure already present in the original samples.

Dislocation densities and crystallite size distributions in nanocrystalline ball-milled fluorides,MF2(M= Ca, Sr, Ba and Cd), determined by X-ray diffraction line-profile analysis

2005 ◽  
Vol 38 (6) ◽  
pp. 912-926 ◽  
Author(s):  
G. Ribárik ◽  
N. Audebrand ◽  
H. Palancher ◽  
T. Ungár ◽  
D. Louër
Keyword(s):  
Crystallite Size ◽  
Line Profile ◽  
Interference Effect ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Line Profile ◽  
Dislocation Densities

The dislocation densities and crystallite size distributions in ball-milled fluorides,MF2(M= Ca, Sr, Ba and Cd), of the fluorite structure type have been determined as a function of milling time by X-ray diffraction line-profile analysis. The treatment has been based on the concept of dislocation contrast to explain strain anisotropy by means of the modified Williamson–Hall and Warren–Averbach approaches and a whole-profile fitting method using physically based functions. In most cases, the measured and calculated patterns are in perfect agreement; however, in some specific cases, the first few measured profiles appear to be narrower than the calculated ones. This discrepancy is interpreted as the result of an interference effect similar to that described by Rafaja, Klemm, Schreiber, Knapp & Kužel [J. Appl. Cryst.(2004),37, 613–620]. By taking into account and correcting for this interference effect, the microstructure of ball-milled fluorides is determined in terms of dislocation structure and size distributions of coherent domains. A weak coalescence of the crystallites is observed at longer milling periods. An incubation period in the evolution of microstrains is in correlation with the homologous temperatures of the fluorides.

scholarly journals X-ray diffraction line profile analysis for defect study in Zr-2.5% Nb material

2004 ◽  
Vol 27 (1) ◽  
pp. 59-67 ◽  
Author(s):  
K. Kapoor ◽  
D. Lahiri ◽  
S. V. R. Rao ◽  
T. Sanyal ◽  
B. P. Kashyap
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Diffraction Line ◽  
Line Profile Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Line Profile
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