Extended defects in ceramics which contained 6wt%Bi4Ti3O12 were studied by means of analytical electron microscopy. Apart from basal plane condensation stacking faults, which were also present in as-received ZnO, extended defects that were related to the presence of Bi4Ti3O12 were observed. In samples which had been sintered at 900C, they lay in the basal plane or in the prismatic {10•0} planes and often formed closed loops. On the other hand, they had serpentine boundaries in specimens which had been sintered at 1200C. The evidence suggested that these were inversion boundaries. Their transmission electron microscopic image characteristics, and the clear presence of Ti at the boundaries, suggested that they formed due to the presence of 2-dimensional coherent precipitates of a Ti-rich phase (perhaps a Zn2TiO4 spinel).

Extended Defects in ZnO Ceramics Containing Bi4Ti3O12 Additive. Makovec, D., Trontelj, M.: Journal of the American Ceramic Society, 1994, 77[5], 1202-8