ISSN:
1600-5767
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Geosciences
,
Physics
Notes:
Detailed measurements have been made of dislocation image widths in X-ray topographs taken under conditions of low absorption (product of linear absorption coefficient and crystal thickness, μt = 0.15) with a silicon specimen and Mo Kα radiation. These have been compared with two theoretical models, the `diffracting-zone' model involving computation of misorientation gradient contours, and the direct-image `mosaic' model using calculations of effective misorientation contours. Neither model completely explains the image widths. The diffracting-zone model, though theoretically more attractive, gives a very poor correlation, probably because of (a) severe photographic limitations and (b) the uncertainty in the reconstruction of the intermediary image in translation topographs. For a given reflection the direct-image mosaic model gives a reasonably good prediction of image widths measured at half peak height. However, the widths in different reflections are not self-consistent; in particular, images in lower-order reflections are significantly wider than those predicted by the model. This implies that contributions from interbranch scattering (giving an intermediary image component) are more important in lower-order reflections, and that such contributions are proportional to the widths obtained from misorientation (rather than misorientation gradient) contours.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0021889875011569
Permalink
