Defect-Related Physical-Profile-Based X-Ray and Neutron Line Profile Analysis

Abstract

Diffraction line broadening is caused by different defects present in crystalline materials: (1) small coherent domains, (2) dislocations, (3) other types of microstrains, (4) twin boundaries, (5) stacking faults, (6) chemical inhomogeneities, and (7) grain-to-grain second-order internal stresses. Line profile analysis provides qualitative and quantitative information about defect types and densities, respectively. Line profiles can broaden, be asymmetric, and be shifted, and these features can be anisotropic in terms of hkl indices. A few thumb rules help qualitative selection of lattice defect types. If the breadths do not increase globally with hkl, the defects are of size type, i.e., either the domain size is small or twinning or faulting, or both, is present. Whenever the breadths increase globally, the defects produce microstrains. Physically based profile functions can be determined for the different defect types and hkl anisotropy. The qualitative input about defect types based on different experimental observations allows adequate quantitative evaluation of the densities of different defect types by using physically modeled profile functions.

Composite Behavior of Lath Martensite Steels Induced by Plastic Strain, a New Paradigm for the Elastic-Plastic Response of Martensitic Steels

“…Line profile analysis has been done on the diffraction patterns measured in the unloaded states of the specimen. These diffraction patterns were evaluated by the Convolutional-Multiple-Whole-Profile (CMWP) fitting procedure based on physically modelled profile functions for dislocations, crystallite size and planar defects [14,15]. The size profile function, I S , is constructed by assuming a logarithmic-normal size distribution of the coherently scattering domains.…”

X-ray diffraction line profile analysis of KBr thin films

“…While, the external biaxial strain produces from the film growth on lattice mismatched substrate [26]. The influence of each defect type on a peak broadening can be separated on the basis of their characteristic hkl dependence and, to some extent, on the basis of their different profile shapes [27]. However, in this article, we only present a quantitative evaluation of size and strain parameters derived from diffracted peak width of KBr films.…”

X-ray line profile analysis—An ideal tool to quantify structural parameters of nanomaterials

“…Generalizing the result of Warren and Averbach, XPA assumes that the intensity distribution of a Bragg reflection measured in the experiment (I meas ) is given as the convolution of the intensities distribution of each individual effect plus background: I meas = I inst * I size * I strain * I pf * ... + BG (4) where I inst is the instrumental function, I size corresponds to size broadening, I strain originates from strain present in the material, I pf is the contribution of planar faults, BG is the background and the dots symbolize, that additional effects can be included in a similar manner.…”

“…Luckily the microstructure also has notable effects on the measured profiles: The width of the reflections increases with decreasing crystallite size, and increasing densities of lattice defects, while a increasingly heterogeneous distribution of lattice defects, heterogeneous local stresses and planar faults cause asymmetric peak broadening. [1][2][3][4][5][6][7][8][9][10][11][12][13] Apart from effects on the x-ray peaks, the background scattering also can include information on the microstructure, for instance on the presence and concentration of point defects. [14][15][16] The whole set of procedures to obtain microstructural parameters from x-ray line profile is called XLPA (x-ray line profile analysis) or XPA (x-ray profile analysis) in the literature.…”