Atomic-Resolution Measurement of Oxygen Concentration in Oxide Materials

Using high-resolution imaging at negative spherical aberration of the objective lens in an aberration-corrected transmission electron microscope, we measure the concentration of oxygen in ∑3{111} twin boundaries in BaTiO ₃ thin films at atomic resolution. On average, 68% of the boundary oxygen sites are occupied, and the others are left vacant. The modified Ti ₂O₉ group unit thus formed reduces the grain boundary energy and provides a way of accommodating oxygen vacancies occurring in oxygen-deficient material by the formation of a nanotwin lamellae structure. The atomically resolved measurement technique offers the potential for studies on oxide materials in which the electronic properties sensitively depend on the local oxygen content.