The various structures of Σ = 3 incoherent twin boundaries in β-phase material were studied by means of high-resolution electron microscopy. The structure of the incoherent twin boundary consisted of an array of structural units which changed its appearance; depending upon its length. The array comprised aligned symmetrical structural units which were composed of 5-, 7- and 6-membered rings, in that order, at short boundaries, both symmetrical and asymmetrical structural units at intermediate boundaries, and zig-zag or obliquely distributed symmetrical structural units at long boundaries. It was known, from tight-binding calculations, that the energy difference between the symmetrical and asymmetrical structural units was not as large if Si atoms were reconstructed. Both structures could then occur. The results of high-resolution electron microscopy were in good agreement with the theoretical calculations.

The Variety of Structures of the Σ = 3 Incoherent Twin Boundary in β-SiC. K.Tanaka, M.Kohyama, M.Iwasa: Materials Science Forum, 1999, 294-296, 187-90