Electron diffraction from periodic 〈111〉 twist grain boundary structures

Abstract

The in situ relaxation of near‐concidence boundaries and structures of exact coincidence boundaries in thin gold bicrystals containing [111] twist boundaries are studied. A previously suggested procedure is applied to the analysis of electron diffraction patterns from such bicrystals obtained with the incidence beam parallel to the rotation axis. It is shown that diffraction patterns of unrelaxed near‐coincidence boundaries can be analysed completely in terms of double diffraction. During relaxation extra reflections emerge that can be ascribed to the generation of secondary grain boundary dislocation networks. In diffraction patterns of exact coincidence boundaries with hexagonal symmetry it is found that spots are present at positions of the reciprocal coincidence lattice points that cannot be caused by double diffraction in the zero order Laue zone. These reflections are due to diffraction from the coincidence lattice in the bicrystal.

Twisting two-dimensional iron sulfide layers into coincident site superlattices via intercalation chemistry

“…40 We adopt the coincident site lattice (CSL) theory to explain experimentally observed rotation angle in the diffraction patterns and formation of FeS superstructures. 41 While CSL theory was initially developed to explain preferred orientations in secondary recrystallization textures in metals, 42,43 it has been frequently used in other contexts to explain grain boundary dislocations, 44 orientation relationship between bicrystals 45,46 and Moiré superlattices. [47][48][49][50][51][52] Commensurate superlattices were observed in several homobilayer hexagonal lattices with preference for certain twist angles over other arbitrary angles.…”

X-ray diffraction by a low-angle twist boundary perpendicular to crystal surface. I. Superstructure factor of screw dislocation superlattice

“…In the last decade electron and X-ray diffraction have been successfully used (a) to detect the periodic structure of low-and high-angle GBs (Sass, Tan & Balluffi, 1975;Carter, Donald & Sass, 1979;Carter, FSll, Ast & Sass, 1981), (b) to study the relaxation effects in the GB (Erlings & Schapink, 1979), (c) to estimate the GB thickness (Budai, Gaudig & Sass, 1979;Carter, Donald & Sass, 1980), and (d) to study the detailed atomic structure of GBs (Guan & Sass, 1973Budai & Sass, 1982).…”