fig3

Figure 3. (A) Antiferrodistortive transition of SrTiO₃ from cubic to tetragonal phase; (B) Metastable phase second harmonic intensity with time after mid-infrared illumination. This figure is quoted with permission^[59]; (C) Schematic of the phonon mode in STO. This figure is quoted with permission^[60]; (D) Atomic structure of the a^-b⁺a^- OOR pattern in an ABO₃ perovskite; (E) Atomic structure of the a^-a^-a^- OOR pattern in an ABO₃ perovskite; (F) Engineering of the OOR patterns between a^-b⁺a^- and a^-a^-a^- structures in CaTiO₃. This figure is quoted with permission^[61]; (G) HAADF-STEM image projection of ScFeO₃ under 15 GPa and at 1,450 °C; (H) Schematic of the LiNbO₃-type crystal structure of ScFeO₃; (I) Polyhedral schematic of the LiNbO₃-type ScFeO₃ crystal structure; (J) Local coordination structure of face-sharing ScO₆ and FeO₆ octahedra stacked along the c-axis. This figure is quoted with permission^[62]. STO: SrTiO₃; OOR: oxygen octahedral rotation; HAADF-STEM: high-angle annular dark-field scanning transmission electron microscopy.