Two-dimensional mapping of polarizations of rhombohedral nanostructures in the tetragonal phase of BaTiO3 by the combined use of the scanning transmission electron microscopy and convergent-beam electron diffraction methods

Nanometer-sized structures with rhombohedral symmetry were discovered in the tetragonal and orthorhombic phases of perovskite-type ferroelectric BaTiO₃, using convergent-beam electron diffraction [K. Tsuda, R. Sano, and M. Tanaka, Phys. Rev. B 86, 214106 (2012)]. The existence of rhombohedral nanostructures indicates an order-disorder character in their phase transformations. In the present study, spatial distributions of the nanostructures have been examined by the combined use of the scanning transmission electron microscopy and convergent-beam electron diffraction methods. Two-dimensional distributions of polarizations of the rhombohedral nanostructures have been visualized in the tetragonal phase of BaTiO₃.