On the detection of expansion at large angle grain boundaries using electron diffraction

A model of the type shown by Brokman and Balluffi in this article, should hold for grain boundary reflections from twist boundaries occurring at positions in reciprocal space on elements of the ''boundary diffraction lattice'' (BDL) which do not contain lattice reflections. In such cases, the intensities scattered by the boundary region and the two unperturbed lattices can be separated to a good approximation, and the scattering from the boundary region can be considered independently. However, in the present case, where the intensity from the grain boundary region, considered separately, would appear close to lattice reflections on the same element of the BDL, it is not clear that this is the case. It may be necessary to perform a more complicated analysis taking account of the total scattering from the grain boundary region and the two adjoining lattices. The purpose of this article is to present such an analysis. The results show that the more complicated analysis is required and a more realistic explanation of the observed result is discussed