Strain Broadening of X-Ray Diffraction Peaks

The line shape caused by lattice distortions in a crystal is reviewed. It is revealed that the broadening of a diffraction peak with indices hkl is related to the mean-square-strain perpendicular to the reflecting (hkl) lattice planes. The strain broadening of line profiles depends on the order of diffraction. The line profiles for a crystal in which the lattice distortions are caused by dislocations are described in detail in this chapter. It is revealed that the anisotropic strain field of dislocations yields a special dependence of peak broadening on indices of reflection. The stronger the screening of the strain fields of dislocations, the longer the tails in the diffraction profiles. For polarized dislocation walls, the diffraction peak is asymmetric, and the antisymmetric component of the profile is determined by the dislocation polarization. It is shown that the strains in nanoparticles resulted by the relaxation of their surfaces also lead to line broadening.

2009 ◽  
Vol 42 (4) ◽  
pp. 673-680 ◽  
Author(s):  
Valeriy A. Luchnikov ◽  
Dimitri A. Ivanov

The diffraction peak position, width and intensity distribution are calculated for the case of a helicoidally twisted crystalline lamella, both analytically and numerically. It is shown that the diffraction peak broadening depends on the orientation of the corresponding reciprocal-space vector with respect to the helicoid axis and the normal to the lamellar basal plane. The equatorial peaks, which are close to the normal direction to the lamellar basal plane, are characterized by the highest azimuthal width. By contrast, the reflections positioned close to the lamellar surface have the smallest azimuthal width. For non-equatorial peaks in the proximity of the twisting axis the intensity has an unusual asymmetric shape. The shape of the microbeam, as well as its position and direction with respect to the lamella, influences the shape of the diffraction peaks in reciprocal space and their appearance in two-dimensional diffractograms. The proposed approach can be useful, for example, for the interpretation of microbeam diffractograms of banded polymer spherulites.


1984 ◽  
Vol 39 (5) ◽  
pp. 481-485 ◽  
Author(s):  
K. Häupl ◽  
P. Wißmann

X-Ray diffraction spectra of thin films may show characteristic interference fringe patterns which wash out with increasing surface roughness. From the intensity of the secondary maxima quantitative data on the roughness can be derived. Model calculations are presented assuming that the distribution of heights about the mean surface level is Gaussian. The theory is applied to explain the diffraction spectra of single-crystal silver films. It is shown that some uncertainty in the results remains due to the influence of lattice distortions


1993 ◽  
Vol 8 (1) ◽  
pp. 2-6 ◽  
Author(s):  
Davor Balzar ◽  
Hassel Ledbetter ◽  
Alexana Roshko

An X-ray diffraction peak-broadening analysis of four oxides is described: La2CuO4 and La1.85M0.15CuO4 (M = Ca,Ba,Sr) high-Tc superconductors. The diffraction line profiles were fitted with a convolution of specimen and instrumental functions, and the specimen peakbroadening angular dependence was analyzed with the Warren-Averbach method. It was found that microstrains and incoherently diffracting domains are highly anisotropic. In the superconductors, stacking-fault probability increases with increasing Tc; microstrain decreases. In La2CuO4, different broadening of (h00) and (0k0) reflections is not caused by stacking faults; it might arise from lower crystallographic symmetry.


1990 ◽  
Vol 34 ◽  
pp. 519-529
Author(s):  
Buckley Crist ◽  
Paul R. Howard

Studies of the shapes of X-ray diffraction peaks from synthetic polymers are still rather uncommon. One probable cause of this situation is the small peak-to-background ratio in most polymer diffraction experiments; it is difficult to achieve precise line profiles for quantitative analysis. Increased utilization of automated data collection/analysis systems and more intense X-ray sources should alleviate this restriction. We suspect, furthermore, that confusion about nomenclature has impeded the acceptance of lineshape analysis for polymers. The peak broadening mechanisms which are generally considered are finite coherence length or crystal size, lattice parameter fluctuation, and displacement disorder of the second kind. Both latter mechanisms have, unfortunately, been referred to as “strains” or “microstrains”. Metallurgists have traditionally expressed displacement disorder as a (length dependent) “microstrain”, and this convention has been adopted in some studies of polymer diffraction. Other work on polymers, however, has termed lattice parameter fluctuation as “microstrain“. The inconsistent use of this term can imply a nonexistent relation between two distinct phenomena.


1998 ◽  
Vol 541 ◽  
Author(s):  
S. Chattopadhyay ◽  
A. Teren ◽  
B.W. Wessels

AbstractThe microstrain in epitaxial BaTiO3 thin films has been investigated using x-ray diffraction. The full width half maximum of the (001) diffraction peaks ranged from 0.12 to 0.49 deg. From the analysis of the angular dependence of the diffraction peak broadening, it is concluded that the broadening is due predominantly to strain. The magnitude of the microstrain decreases sharply with increasing film thickness.


2019 ◽  
Vol 43 (5) ◽  
pp. 1903-1911 ◽  
Author(s):  
Ahmed A. Al-Tabbakh ◽  
Nilgun Karatepe ◽  
Aseel B. Al-Zubaidi ◽  
Aida Benchaabane ◽  
Natheer B. Mahmood

2010 ◽  
Vol 663-665 ◽  
pp. 166-169
Author(s):  
Qing Quan Xiao ◽  
Quan Xie ◽  
Ke Jie Zhao ◽  
Zhi Qiang Yu

Semiconducting Mg2Si films were fabricated on Si (111) substrates by magnetron sputtering and subsequent annealing, and the effects of sputtering pressure on the Mg2Si film growth were studied. The structural and morphological properties of Mg2Si films were investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the Mg2Si (220) main diffraction peak intensity increased and then decreased with the increasing of sputtering pressure. The (220) diffraction peak got its maximum at 3.0 Pa sputtering pressure. The intensity of Mg2Si (200) and (400) diffraction peaks increased rapidly as the sputtering pressure decreased when the pressure was lower than 1.5 Pa. The films prepared at higher sputtering pressure had very irregular microstructures, and the surface of semiconducting Mg2Si films became smoother with the decreasing of the sputtering pressure.


2004 ◽  
Vol 51 (1) ◽  
pp. 59-63 ◽  
Author(s):  
Sanjay K. Rai ◽  
Anish Kumar ◽  
Vani Shankar ◽  
T. Jayakumar ◽  
K. Bhanu Sankara Rao ◽  
...  

2018 ◽  
Vol 10 (3) ◽  
pp. 409-412
Author(s):  
Shihua Zhao

ZnO/AAM (anodic alumina membrane) arrays were prepared by an electrodeposition method and X-ray diffraction (XRD) patterns show that the characteristic diffraction peaks of ZnO appear, such as the lattice planes of (100), (002), and (102), moreover, the diffraction peaks of Al2O3 are dominated. Scanning electron microscopy (SEM) images show that the average sizes of the ZnO particles are about 100 nm corresponding to the channel diameters of AAM, and the ZnO arrays are composed of those close particles linked together. The photoluminescence emission spectra express that the as-prepared ZnO arrays can give out relatively pure ultraviolet light (395 nm) from the excitons.


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