Convergent-beam electron diffraction and Z-contrast imaging were used to study O-associated defects such as flat inversion domain boundaries, dislocations and interfaces in sintered samples. The structures of the defects were derived directly from atomic-resolution Z-contrast images. The flat inversion domain boundaries contained a single Al-O octahedral layer, and had a stacking sequence of the form: … bAaB-bAc-CaAc …, where -cAb- indicated a single octahedral layer. The expansion at the flat inversion domain boundaries was measured to be about 0.06nm. The interfaces between 2H- and polytypoid AlN were also found to be inversion domain boundaries, but their stacking sequence differed from that of the flat inversion domain boundaries.

Atomic Structures of Oxygen-Associated Defects in Sintered Aluminum Nitride Ceramics. Y.Yan, S.J.Pennycook, M.Terauchi, M.Tanaka: Microscopy and Microanalysis, 1999, 5[5], 352-7