The X-ray diffraction Topography technique
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X-Ray diffraction Topography (XRT) is a non-destructive imaging technique based on Bragg diffraction. It provides a two dimensional intensity mapping of the beam(s) diffracted by a crystal. It is used for the visualisation of defects (dislocations, twins, domain walls, inclusions, impurity distribution, …) present in the crystal volume. More exactly, it records the long range distortion fields and/or the strain fields associated with a macroscopic crystal. This becomes possible, because these distortion fields may affect the diffracted intensity, so give "contrast" (nonhomogeneous intensity distribution) in the image.
In this way topography is a study of the fine structure of a Bragg spot which contains the information about the departures from the perfect crystal structure (which is investigated by structure determination methods and assumed as known), that is the defect structure. The basic principle of X-ray topography is shown in figure |
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Last Updated on Monday, 19 September 2011 15:52
