The grain-boundary atomic structure of a high-purity α-phase bicrystal was investigated by means of atomic-resolution high-voltage transmission electron microscopy. The angular relationship of the boundary corresponded to a 70.5° rotation around the <11▪0> axis. The boundary plane was parallel to the (00▪1) plane of one of the crystals and the
(11▪2) plane of the other. The structural unit of the boundary consisted of 5-7-6-6-6-6-membered rings. The atomic sites and atomic species of both Si and C in the boundary could be distinguished in the atomic-resolution electron microscopic images. All of the atomic pairs, apart from just 1 pair in the unit period of the boundary, consisted of unlike atoms. The pair of like atoms consisted of Si, and was located between the 5- and 7-membered rings. The identity of the 3-fold coordinated atom was shown directly, by the contrast in the electron microscopic image, to be C.
Atomic Site Determination of a High-Purity SiC Grain Boundary. E.Takuma, H.Ichinose: Philosophical Magazine A, 2002, 82, 857-66