Materials Applications of Aberration-Corrected STEM

recently achieved the first direct image of a crystal at sub-Angstrom resolution, as shown in Fig. 1. [1] The 0.78 Angstrom spacing of the dumbbell seen in Si〈112 〉 is clearly resolved in the image and the Fourier transform indicates a probe size of 0.6 Ångstrom. This small probe allows the imaging of light atom columns next to heavy columns. Oxygen columns can now be imaged in the 〈100 〉 projection in perovskites and related materials such as the manganites and high temperature superconductors. Figure 2 shows oxygen columns in SrTiO3 with relative contrast close to that predicted from simulations using the experimentally determined aberration parameters. Fig 2: SrTiO3 〈100 〉 imaged with a 0.6 Å probe showing O columns, compared to simulated line traces Sr-O-Sr and O-TiO-O. Simulations without O columns show no peaks at the oxygen locations