Dissociation of the 1/3〈1¯101〉 dislocation and formation of the anion stacking fault on the basal plane in α-Al2O3

Dislocation structures in the (0 0 0 1)/〈11¯00〉 2° tilt grain boundary of alumina (α-Al2O3) were investigated by atomic-resolution transmission electron microscopy (TEM). We found that the grain boundary basically consists of a periodic array of 1/3[1¯101], 1/3[01¯11], and 1/3[10 1¯ 1] dislocations, and these dislocations were dissociated into two partial dislocations with a stacking fault in between on the (0 0 0 1) plane. Atomic-resolution scanning TEM analysis revealed that the stacking fault is present on the anion sublattice, which has not been observed in alumina so far. The presence of the stable (0 0 0 1) anion stacking faults was theoretically supported using a first-principles calculation. Combining experimental and theoretical results, we demonstrate the dissociation reactions of the 1/3〈1¯101〉 dislocation and the associated stacking fault.