Direct observation of oxygen atoms in rutile titanium dioxide by spherical aberrationcorrected high-resolution transmission electron microscopy

Abstract

We have developed a spherical aberration corrected transmission electron microscopy(Cs-corrected TEM) technique that allows us to obtain clearer images in real space than everbefore. We applied this technique to titanium oxide, in which light elements such as oxygenare difficult to observe using TEM because of its small cross section and electronicdamage. In the present study, we successfully observed oxygen atoms in rutileTiO2. In addition, this direct observation of oxygen atoms enabled us to study the Magnéli structure(TinO2n−1), which is caused by oxygen vacancies. These vacancies caused an atomic relaxation of thetitanium and oxygen atoms. The relaxed atoms formed a characteristic shear structureof rutile titanium dioxide phase. This shear structure of the Magnéli structure(TinO2n−1) was visualized with a spatial resolution of 0.119 nm. At the same time, the selected areadiffraction (SAD) pattern of the defect structure was obtained. Additional spots wereshown inside the rutile [110] spot. We made structural models of the shear structureand simulated the diffraction pattern and images using a multi-slice simulation.Additional spots in the simulated diffraction patterns accurately reconstructed theexperimental data. We also considered the possibility of the real-space analysis of localstructures using spherical aberration corrected transmission electron microscopy.