THE STRUCTURES OF INVERSION DOMAIN BOUNDARIES IN ALN CERAMICS

The structures of inversion domain boundaries in sintered AlN ceramics were studied by convergent-beam electron diffraction and high-resolut ion electron microscopy. The displacement vectors at a flat and a curv ed inversion domain boundary were determined to be R(F) = (0.11 +/- 0. 02)[0001] + epsilon(F), where epsilon(F) = (0.02 +/- 0.05)[1 (1) over bar 00] and R(c) = (0.17 +/- 0.02)[0001] + epsilon(c) where epsilon(c) = (0.03 +/- 0.01)[(1) over bar 100] respectively. An interfacial mode l was derived for the flat inversion domain boundary. The model contai ns a single Al-O(N) octahedron layer at the interface and has a stacki ng sequence of ... cAaC-cAb-BaAb ..., where -cAb- indicates the single Al-O(N) octahedron layer. A high-resolution electron microscopy study supported the present model.