Atomic structures of oxygen-associated defects in sintered aluminum nitride ceramics

Convergent-beam electron diffraction and Z-contrast imaging are used to study oxygen-associated defects, flat inversion domain boundaries, dislocations, and interfaces in sintered AlN ceramics. The structures of these defects are directly derived from atomic-resolution Z-contrast images. The flat inversion domain boundaries contain a single Al-O octahedral layer and have a stacking sequence of . . .bAaB-bAc-CaAc. ., where -cAb- indicates the single octahedral layer. The expansion at the flat inversion domain boundaries is measured to be 0.06 (±0.02) nm. The interfaces between 2H- and polytypoid-AlN are found to be also inversion domain boundaries but their stacking sequence differs from that of the flat inversion domain boundaries.