Relative stability between two types of reconstructed models of the {122} Σ=9 coincidence boundary in cubic SiC was examined by using the ab initio pseudopotential method based on the density-functional theory. Results were compared with high-resolution transmission electron microscopy observations of SiC polycrystalline films. A zig-zag model consisting of zig-zag arrangement of 2 sets of 5- and 7-membered rings was more stable than a straight model consisting of straight arrangement of 5-, 6- and 7-membered rings, because of larger bond stretching in the latter model. The former model requires a rigid-body translation parallel to the interface. This may cause large strain at the triple junction with the {111} Σ=3 boundaries, although this could be avoided by introducing a step at the junction. The high-resolution transmission electron microscopy observations had clearly shown the presence of the zig-zag model and the step at the triple junction.

First-Principles Study of a {122} Σ=9 Boundary in Cubic SiC - Relative Stability between Zig-Zag and Straight Models and Comparison with Electron Microscopy Observation. M.Kohyama, K.Tanaka, S.Tanaka: Materials Transactions, 2004, 45[5], 1461-4