Lamellar and bundled domain rotations in barium titanate

Abstract

Cross-correlation of electron backscatter diffraction patterns has been used to generate rotation maps of single crystals of tetragonal barium titanate (BaTiO3) containing multiple lamellae and bundles of ≈ 90° domains. Rotation measurement angular resolutions of 0.1 mrad (0.006°) and spatial resolutions of 30 nm are demonstrated on structures with approximately 1 μm domains extending over 10s of μm. The material orientations demonstrated considerable microstructural dependence: c domains, with polarization perpendicular to a free surface, exhibited little within-domain rotation variation while a-domains, with polarization parallel to the surface, exhibited considerable within-domain variation, particularly in the larger lamellar domain structure. In both lamellar and bundled structures, the maximum a–c between-domain rotation was approximately equal to the value θr ≈ 0.63° (11 mrad) predicted by a rigid rotation of tetragonal BaTiO3 unit cells across the domain boundary. However, in both structures there was gradual variation in rotation throughout, especially adjacent to domain boundaries, suggesting that a rigid rotation model predicts too abrupt a unit cell and polarization rotation. A new BaTiO3 compound defect was deduced through identification of a double integral surface rotation 2θr. The double rotation is indicative of a low-angle grain boundary terminating at a surface by a confined 90° domain.