Analysis of planar defects in Nb205- and Bi203-doped BaTiO3 ceramics.

The structure and chemistry of planar defects in Nb₂O₅- and Bi₂O₃-doped BaTiO₃ grains exhibiting “core-shell” microstructures has been examined. In addition to 90° ferroelectric domain boundaries within the core, twins and stacking faults were observed both with interfaces lying along {111}. While the twins bisected grains completely, stacking faults were observed only in the shell region and the latter are enriched in Nb and Bi relative to the surrounding matrix. A stacking fault structure is proposed based on a double BiO₃^3- “layer with partial cation site occupancy by Ba²⁺ and charge compensation by Nb⁵⁺ substitution in adjacent octahedral sites.