Inversion domain boundaries in ZnO ceramics

Inversion domain boundaries (IDB's) in ZnO ceramics, associated with Sb₂O₃ doping, have been characterized using a range of electron microscopy techniques. The IDB's lie primarily on basal planes, but frequently are stepped along prismatic planes. The basal IDB can be characterized as (i) an inversion that causes an antisite exchange of cations and anions across the boundary, (ii) an effective displacement of the sixfold screw axis in the wurtzite structure vectors by a translation of 1/3 and (iii) a displacement normal to the boundary. Significant Sb segregation is detected in the basal IDB segments in agreement with previous work, and in ceramics doped with Sb₂O₃ and Bi₂O₃. These IDB's contained both Sb and Bi, suggesting that while Bi does not participate in IDB nucleation, it resides in the boundary. Comparison of experimental and calculated HREM images suggests that the IDB is composed of a monolayer of Type I (111) zinc antimonate spinel, consisting of a single layer of octahedrally coordinated zinc and antimony cations.