Practical Electron Microscopy and Database

Figure 133a shows a STEM Z-contrast image of an 8° [0 0 1] tilt grain boundary in SrTiO₃ in the [0 0 1] orientation, indicating two adjacent grains with cubic symmetry and five dislocation cores (dark ovals) at the grain boundary. Figure 133a (b) shows one of the dislocation cores at a higher magnification. The brighter columns surrounding the core represent the Sr columns, while the less bright columns represent the Ti–O columns. Due to the small scattering amplitude of oxygen, the pure O columns are not visible.

Figure133b shows the structure of spinel Li[Mn₂]O₄ along the cubic [110] axis. Figure 133b (b) is an HAADF STEM image, where only the Mn atoms of the diamond periphery are visible, while the Li and O atoms are invisible.

(a)	(b)

Figure 133b. (a) Atomic structural model of LMO (spinel Li[Mn2]O4) viewed along the cubic [110] axis. Li atoms (green) occupy tetrahedral sites, and Mn atoms (purple) occupy octahedral sites within a face-centered-cubic array of oxygen atoms (red). (b) Corresponding HAADF STEM image in which bright spots correspond to columns of Mn. Among these, the brighter spots are associated with Mn columns containing a higher number of atoms. [2]

[1] R.F. Klie, I. Arslan, N.D. Browning, Atomic resolution electron energy-loss spectroscopy, Journal of Electron Spectroscopy and Related Phenomena 143 (2005) 105–115.
[2] Charles D. Amos, Manuel A. Roldan, Maria Varela, John B. Goodenough, and Paulo J. Ferreira, Revealing the Reconstructed Surface of Li[Mn2]O4, Nano Lett. 2016, 16, 2899−2906.