X-ray line profile analysis

Jf-Ray Methods. - A -ray line-broadening is often used to estimate the mean size of supported metal crystallites and introductory accounts of the technique in relation to catalyst examination are available. Recently, more detailed information is being extracted, e.g., the distribution of crystallite size, the presence of strain, and an indication of crystallite shape. The crystallite size distribution obtained from X-ray line-profile analysis can be complicated by spurious oscillations. A method for the smoothing of crystallite size distribution by use of a least-squares procedure with a stabilization scheme has been described (with references to other methods). One such correction procedure was appUed to obtain crystallite size distributions in... 

UNG 99] UNGAR T., The dislocation based model of strain broadening in x-ray line profile analysis , in SNYDER R.L., FIALA J., BUNGE H.J. (eds.). Defect and microstructure analysis by diffraction, lUCr Monographs on crystallography, no. 10, Oxford University Press, p. 264-317,1999. 

Csiszar, G., Vngar, T., Jaro, M., 2013. Correlation between the sub-structure parameters and the manufacturing technologies of metal threads in historical textiles using X-ray line profile analysis. Appl. Phys. A 111 (3), 897-906. 

Powder X-ray diffraction (XRD) patterns of the catalysts separated from the reaction mixture were measured using a Shimadzu VD-1 diffractometer with CuKa radiation. The mean crystallite size (D. ) of iron metal in a catalyst was calculated from the half-maximum breadth of the (110) peak of a-Fe after correction for instrumental broadening (ref. 10). The crystallite size distributions (CSD) of iron in some catalysts were obtained according to the Fourier transform method (Stokes method) for X-ray line profile analysis (ref. 11). 

Topas A fundamental parameters approach to X ray line profile fitting, R. W. Cheary and A. A. Coelho, J. Appl. Crystallogr., 1992, 25, 109 121, Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers, R. W. Cheary, A. A. Coelho and J. P. Cline, J. Res. Natl. Inst. Stand. TechnoL, 2004, 109, 1 25, TOPAS Academic by Alan Coelho, ISIS and TOPAS V3 General profile and structure analysis software for powder diffraction data. User s Manual, (2005) Bruker AXS, Karlsruhe, Germany Fundamental parameters Rietveld with macro language... 

When applied to the XRD patterns of Fig. 4.5, average diameters of 4.2 and 2.5 nm are found for the catalysts with 2.4 and 1.1 wt% Pd, respectively. X-ray line broadening provides a quick but not always reliable estimate of the particle size. Better procedures to determine particle sizes from X-ray diffraction are based on line-profile analysis with Fourier transform methods. 

Better procedures for determining particle sizes from X-ray diffraction are based on line profile analysis with Fourier transform methods. The average size is obtained from the first derivative of the cosine coefficients and the distribution of particle sizes from the second derivative. When used in this way, XRD offers a fundamental advantage over electron microscopy, because it samples a much larger portion of the catalyst. The reader is referred to publications by Cohen and coworkers for more details and examples [4,10,11],... 

X-ray powder diffraction data for all samples were collected via a Phillips x-ray diffractometer with a copper target tube and a diffracted beam monochromater. Ruthenium and RuC>2 particle sizes were estimated by x-ray line shape profile analysis using a single profile technique which provides diffracting particle size, microstrain, and the particle size distribution (10). 

Another contribution to variations of intrinsic activity is the different number of defects and amount of disorder in the metallic Cu phase. This disorder can manifest itself in the form of lattice strain detectable, for example, by line profile analysis of X-ray diffraction (XRD) peaks [73], 63Cu nuclear magnetic resonance lines [74], or as an increased disorder parameter (Debye-Waller factor) derived from extended X-ray absorption fine structure spectroscopy [75], Strained copper has been shown theoretically [76] and experimentally [77] to have different adsorptive properties compared to unstrained surfaces. Strain (i.e. local variation in the lattice parameter) is known to shift the center of the d-band and alter the interactions of metal surface and absorbate [78]. The origin of strain and defects in Cu/ZnO is probably related to the crystallization of kinetically trapped nonideal Cu in close interfacial contact to the oxide during catalyst activation at mild conditions. A correlation of the concentration of planar defects in the Cu particles with the catalytic activity in methanol synthesis was observed in a series of industrial Cu/Zn0/Al203 catalysts by Kasatkin et al. [57]. Planar defects like stacking faults and twin boundaries can also be observed by HRTEM and are marked with arrows in Figure 5.3.8C [58],... 

BOU 01b] BOULLE A., LEGRAND C., GUINEBRETIERE R., MERCURIO J.P., DAUGER A., Application of X-ray diffraction line profile analysis to the study of planar faults in layered Bi - containing perovskites , J. Appl. Cryst., vol. 34, p. 699-703,2001. 

DEL 82] DELHEZ R., DE KEIJSER T.H., MITTEMEIJER E.J., Determination of crystallite size and lattice distorsions through x-ray diffraction line profile analysis , Fresenius Z Anal. Chem., vol. 312, p. 1-16, 1982. 

SUT 95] SUTTA P., JACKLIAK Q., TVAROZEK V., NOVOTNY I., X-ray diffraction line profile analysis of ZnO thin films deposited on Al-Si02-si substrates . Science and technology of electroceramic thin films, Kluwer Academic Publishing, p. 327-334,1995. 

Polyacetylene films produced in this way are well-aligned and show a high de ee of crystalhnity as evidenced by the x-ray photograph shown in figure 2. This diffraction pattern was obtained from a film of stretch ratio 1/1q =11 [17]. Line profile analysis of the various reflections shows that the polyacetylene films are composed of uniaxiaUy oriented paracrystaUites with dimensions of 50A perpendicular to, and 80A parallel to the chain... 

Grinding and polishing can also change the surface stress patterns, distortions which could later lead to crack formation and fracture. X-ray diffraction line profile analysis appears to be the best method for determining residual stresses, a method which can be applied to polycrystalline materials as well as single crystals. 

---