HRTEM of Screw Dislocations in a Small Angle Grain Boundary

The HRTEM picture shows sets of {111} lattice planes for a tilt boundary on {111}. There are three sets of screw dislocations, but only one set can be seen.
The left picture is an overview. The small angle grain boundary is inclined (it is essentially contained between the two red lines); to the far left or right just one of the two grain is seen.
Depending on the local thickness of the grains in the area where they overlap, grain one or grain two dominates the picture.
 
Traces of the two grains are marked in red and blue; the red trace has been shifted to show the twist angle (and the extension of the boundary). The enlargement with a tracing of a {111} plane shows the effect of the screw dislocation.

HRTEM ofscrew dislocations
HRTEM ofscrew dislocations
 

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go to 7.2.2 Case Studies: Small Angle Grain Boundaries in Silicon I

© H. Föll (Defects - Script)