fig6

Figure 6. (A) Schematic illustration of the structural transformation process of the 2D-layered perovskite ALaTa₂O₇ (A = Rb, K, Na) through ion exchange. This figure is quoted with permission^[76]; (B) Ball-and-stick model depicting the standard layered perovskite structure; (C) Schematic of the cubic pyrochlore structure; (D) Plan-view HRTEM image of the DTO film grown on the LTO substrate; (E) HRTEM image of the DTO film in the DTO/LTO interface region, with the corresponding cross-sectional selected area ED (SAED) pattern shown in the lower left corner and an enlarged ED image in the upper right corner. This figure is quoted with permission^[77]; (F) Structural variations of Ln₂Ti₂O₇ compounds depending on the ionic radius ratio of the different cations VIIIA³⁺ and VIB^4+. This figure is quoted with permission^[78]; (G) Projections of the single-crystal Sm₂Ti₂O₇ along the [100] and [010] directions; (H) Calculated diffraction pattern and structural diagram of monoclinic twin crystals; (I) SAED pattern of single-crystal Sm₂Ti₂O₇; (J) Cross-sectional HR-TEM image of Sm₂Ti₂O₇; (K) STEM-HAADF image of Sm₂Ti₂O_7. This figure is quoted with permission^[79]. HRTEM: High-Resolution transmission electron microscopy; SAED: selected area ED; ED: electron diffraction; DTO: Dy₂Ti₂O₇; LTO: La₂Ti₂O₇; STEM-HAADF:scanning transmission electron microscopy - high-angle annular dark field.