This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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The superlattices of two perovskites SrTiO₃ and LaTiO₃have many important properties of naturally occurring charge-ordered systems, i.e. mixed-valence configurations near half-filling. Their lattice constants (see SrTiO₃ and LaTiO₃) are relatively well matched, and the continuity of the TiO₆ octahedral lattice across the superlattice minimizes the perturbation of the electronic states near the chemical potential [1-2].

In HAADF z-contrast imaging mode, the intensity of electron scattering by the atoms depends on the atomic number Z. For the superlattice structure consisting of LaTiO₃ and SrTiO₃ layers, the brightest features are columns of La ions, the second brightest features are columns of Sr ions, and the Ti ions are weakly visible in between the LaTiO₃ and SrTiO₃ layers as shown in Figure 3519. The oxygen ions are not visible due to the much lower atomic number. Note that the number of the LaTiO₃ and SrTiO₃ layers is determined by the deposition recipe.

Figure 3519. HAADF image of superlattice structures consisting of LaTiO₃ and SrTiO₃ layers. The imaging optical axis is the [100] zone axis of the crystals. Adapted from [3].

[1] Sunstrom, J. E. IV, Kauzlarich, S.M. & Klavins, P. Synthesis, structure, and properties of La1-xSrxTiO3 (0 ≤ x ≤ 1). Chem. Mater. 4, 346–353 (1992).
[2] Kahn, A. H. & Leyendecker, A. J. Electronic energy bands in strontium titanate. Phys. Rev. 135, A1321–A1325 (1964).
[3] A. Ohtomo, D. A. Muller, J. L. Grazul and H. Y. Hwang, Artificial charge-modulation in atomic-scale perovskite titanate superlattices, Nature 419, 378-380.