Electron diffraction study of the faceting of tilt grain boundaries in NiO

Abstract

The diffraction effects expected from a periodically faceted boundary containing a periodic array of dislocations in the long facet have been analysed. The characteristic manifestation in reciprocal space of periodic faceting was identified as the occurrence of bundles of reciprocal lattice rods; within each bundle the rods are displaced with respect to each other parallel to their length in a manner related to the facet geometry. Electron diffraction and microscopy were used to study the facet structure of tilt boundaries in NiO, and the boundary structure deduced from the observed diffraction effects was in good agreement with the imaging observations. In those cases where there was only one type of dislocation present in the long facet, it was possible to determine the average boundary plane, the dislocation spacing in the long facet, the facet period and the facet height from electron diffraction observations. This technique is especially useful for large-angle boundaries having high-index rotation axes, where little detailed information can be obtained using imaging techniques.