ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
An attempt has been made to use the general expression derived by Mitra for the intensity of X-rays diffracted by a cluster of two-dimensional identical curved crystallites in studying the changes expected in the diffraction pattern when the curvature of the crystallite is changed. For this purpose, the previous expression has been modified into a form suitable for numerical computation. The modified expression for the intensity is expressed as a finite series of terms containing Bessel functions of zero order only. Further simplification is arrived at for the case of a cluster of crystallites consisting of single arcs only. On the basis of the expression derived, the intensity diffracted at different angles by a cluster of curved crystallites consisting of single arcs of different curvatures has been computed numerically. For studying the effect of different curvatures, calculations have been carried out for arcs subtending 0, 10, 20, 30, 60 and 90° respectively at the centre of curvature for two different values of the total number of atoms on an arc. Where the total number of atoms on each arc is 20, there is no appreciable variation with curvature of the displacements of the maxima from the Bragg angle. Intensity maxima and line profiles remain practically identical for all values of curvature for this value of the total number of atoms. However, when the total number of atoms on each arc is 4, the shifts in the positions of the maxima and the broadening of the line profile become more pronounced and the peak shifts increase, though by a small amount, as the curvature increases.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739468000422
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