Microscale Mapping of Structure and Stress in Barium Titanate

Cross-correlation of electron backscatter diffraction (EBSD) patterns was used to generate rotation, strain, and stress maps of single-crystal tetragonal barium titanate (BaTiO₃) containing isolated, small, sub-micrometer a domains separated from a c-domain matrix by 90° domain boundaries. Spatial resolution of about 30 nm was demonstrated over 5 μm maps, with rotation and strain resolutions of approximately 10^-4. The magnitudes of surface strains and, especially, rotations peaked within and adjacent to isolated domains at values of approximately 10^-2, i.e., the tetragonal distortion of BaTiO₃. The conjugate stresses between a domains peaked at about 1 GPa, and principal stress analysis suggested that stable microcrack formation in the c domain was possible. The results clearly demonstrate the applicability of EBSD to advanced multilayer ceramic capacitor reliability and strongly support the coupling between the electrical performance and underlying mechanical state of BaTiO₃-containing devices.