The dislocation model of strain anisotropy in whole powder-pattern fitting: the case of an Li–Mn cubic spinel

1999 ◽  
Vol 32 (2) ◽  
pp. 290-295 ◽  
Author(s):  
T. Ungár ◽  
M. Leoni ◽  
P. Scardi
Keyword(s):  
Structure Refinement ◽  
Domain Size ◽  
Powder Pattern ◽  
Dislocation Model ◽  
Coherent Domain Size ◽  
Strain Anisotropy ◽  
Average Dislocation Density ◽  
Dislocation Arrangement ◽  
Profile Fitting ◽  
Coherent Domain

Anisotropic strain broadening in X-ray or neutron powder diffraction can cause severe difficulties in whole powder-pattern fitting and Rietveld structure refinement. Several phenomenological models have been proposed to deal with this problem. These, however, lack physically sound bases. In the present work the dislocation-based model of strain anisotropy is applied in the Fourier formalism of profile fitting. It is shown that the anisotropic contrast of dislocations can fully account for strain anisotropy. A few physically sound parameters, namely the average dislocation density, the average coherent domain size, the dislocation arrangement parameter and the dislocation contrast factors, enable a perfect profile fitting to the powder pattern of a cubic Li–Mn spinel obtained at the Daresbury synchrotron storage ring.

Line profile analysis: pattern modellingversusprofile fitting

2006 ◽  
Vol 39 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Paolo Scardi ◽  
Matteo Leoni
Keyword(s):  
Line Profile ◽  
Powder Diffraction ◽  
Profile Analysis ◽  
Domain Size ◽  
Systematic Errors ◽  
Powder Pattern ◽  
Line Profile Analysis ◽  
Microstructural Parameters ◽  
Profile Fitting ◽  
Transmission Electron

Powder diffraction data collected on a nanocrystalline ceria sample within a round robin conducted by the IUCr Commission on Powder Diffraction were analysed by two alternative approaches: (i) whole-powder-pattern modelling based upon a fundamental microstructural parameters approach, and (ii) a traditional whole-powder-pattern fitting followed by Williamson–Hall and Warren–Averbach analysis. While the former gives results in close agreement with those of transmission electron microscopy, the latter tends to overestimate the domain size effect, providing size values about 20% smaller. The origin of the discrepancy can be traced back to a substantial inadequacy of profile fitting with Voigt profiles, which leads to systematic errors in the following line profile analysis by traditional methods. However, independently of the model, those systematic errors seem to have little effect on the volume-weighted mean size.

Distribution of Dislocation Density in Tubes from Zr-Based Alloys by X-Ray Data

2005 ◽  
Vol 105 ◽  
pp. 89-94 ◽  
Author(s):  
Margarita Isaenkova ◽  
Yuriy Perlovich
Keyword(s):  
Dislocation Density ◽  
Domain Size ◽  
Ray Method ◽  
Coherent Domain Size ◽  
Texture Measurement ◽  
Burgers Vector ◽  
X Ray ◽  
Pole Figures ◽  
Coherent Domain

As applied to tubes from Zr-based alloys, the X-ray method was developed to determine the dislocation density distribution in a-Zr depending on the orientation of Burgers vector. The method consists in registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in generalized pole figures. Obtained data testify that the dislocation density varies within very wide intervals of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the constructed dislocation distributions are closely related to the crystallographic texture of studied tubes.

scholarly journals Superconducting properties of very high quality NbN thin films grown by pulsed laser deposition

2019 ◽  
Vol 70 (7) ◽  
pp. 89-94
Author(s):  
Serhii Volkov ◽  
Maros Gregor ◽  
Tomas Roch ◽  
Leonid Satrapinskyy ◽  
Branislav Grančič ◽  
...  
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Pulsed Laser ◽  
Domain Size ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Si Substrate ◽  
Coherent Domain Size ◽  
Coherent Domain

Abstract In this work, we study the effect of the various substrates on the growth and superconducting properties of NbN thin films grown by using pulsed laser ablation in a N2 + 1%H2 atmosphere on MgO, Al2O3 and Si substrates. Structural and superconducting analyses of the films demonstrate that using MgO and Al2O3 substrates can significantly improve the film properties compared to Si substrate. The X-ray diffraction data indicate that MgO and Al2O3 substrates produce highly oriented superconducting NbN films with large coherent domain size in the out-of plane direction on the order of layer thickness and with a superconducting transition temperature of 13.1 K and 15.2 K, respectively. On the other hand, the NbN film grown on the Si substrate exhibits random polycrystalline orientation. Together with the smallest coherent domain size it leads to the lower critical temperature of 8.3 K. Finally, by using a passivation surface layer we are able to improve superconducting properties of NbN thin film and we observe superconducting transition temperature 16.6 K, the one of the highest value reported so far for 50 nm thick NbN film on sapphire.

Inhomogeneous Distribution of Dislocation Density as Manifestation of Multiscale Structure in Tubes from Zr - Based Alloys

2003 ◽  
Vol 779 ◽  
Author(s):  
Yuriy Perlovich ◽  
Margarita Isaenkova
Keyword(s):  
Dislocation Density ◽  
Domain Size ◽  
Nuclear Industry ◽  
Ray Method ◽  
Coherent Domain Size ◽  
Texture Measurement ◽  
Burgers Vector ◽  
X Ray ◽  
Pole Figures ◽  
Coherent Domain

AbstractAn X-ray method was developed to determine the dislocation density in metal materials as a distribution depending on the orientation of Burgers vector. The method includes registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in the generalized pole figures. The method was used to determine the dislocation density in tubes of Zr-based alloys for nuclear industry. Obtained data show, that the dislocation density varies within very wide interval of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the dislocation distribution in tubes are closely related to their crystallographic texture.

Warren-Averbach Analysis of Coherent Domain Size in PbZr0.2Ti0.8O3 Thin Films

2008 ◽  
Vol 52 (3) ◽  
pp. 627-630
Author(s):  
D. Y. Kwon ◽  
X. D. Zhang ◽  
Bog G. Kim
Keyword(s):  
Thin Films ◽  
Domain Size ◽  
Coherent Domain Size ◽  
Coherent Domain

The Effect of Coherent Domain Size on the Insertion Activity of Nanocrystalline RuO[sub 2]

2005 ◽  
Vol 152 (8) ◽  
pp. A1613 ◽  
Author(s):  
Jakub Jirkovský ◽  
Marina Makarova ◽  
Petr Krtil
Keyword(s):  
Domain Size ◽  
Coherent Domain Size ◽  
Coherent Domain

Whole Powder Pattern Modelling of cubic metal powders deformed by high energy milling

2007 ◽  
Vol 222 (3-4) ◽  
Author(s):  
Paolo Scardi ◽  
Matteo Leoni ◽  
Mirco D'Incau
Keyword(s):  
Analytical Approach ◽  
Cell Parameter ◽  
Domain Size ◽  
High Energy ◽  
Powder Pattern ◽  
Metal Powders ◽  
Cubic Metals ◽  
High Energy Milling ◽  
Average Dislocation Density ◽  
Detailed Picture

A Whole Powder Pattern Modelling of the diffraction pattern has been used to study the effect of grinding on some cubic metal powders: crystalline domain size distribution, unit cell parameter average dislocation density, effective outer cut-off radius, effective (screw-edge) dislocation character and faulting probabilities provide a detailed picture of the microstructure of heavily deformed metals. Besides proving the effectiveness of the analytical approach, the present study also suggests some generalization in the behaviour of pure powders of cubic metals subjected to an extensive high-energy milling.

Microstructure and Residual Stress in T40 Titanium after Tensile Test

2017 ◽  
Vol 905 ◽  
pp. 17-24 ◽  
Author(s):  
Sebastian Wroński ◽  
Krzysztof Wierzbanowski ◽  
Mariusz Jędrychowski ◽  
Jacek Tarasiuk ◽  
Marcin Wronski ◽  
...  
Keyword(s):  
Residual Stress ◽  
Tensile Test ◽  
Rolling Direction ◽  
Domain Size ◽  
Deformation Mechanisms ◽  
Test Material ◽  
Coherent Domain Size ◽  
Material Characteristics ◽  
Average Grain Size ◽  
Coherent Domain

The goal work of this work is to describe the qualitative and quantitative behaviour of titanium T40 during tensile test. Material characteristics were determined using EBSD and X-ray techniques. Textures, twin boundary fractions, residual stresses and coherent domain size were determined. It was found that deformation mechanisms and microstructure characteristics are different in the samples stretched along rolling and transverse directions. For example the average grain size, as determined from EBSD measurements, is higher in the sample stretched along rolling direction. Also smaller coherent domains form and residual stress is more easily relaxed in this sample. A strong appearance of tensile twins was observed in the samples deformed along transverse direction. In the present paper a complex study of material characteristics and deformation mechanisms is presented. A special emphasis is done on residual stress characteristics determined in the samples stretched in two perpendicular directions.

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