Extended Data Fig. 3: Oxygen octahedral rotation configuration at a head-to-tail ferroelastic twin boundary.

(a)STEM-HAADF image overlaid with a Pb displacement map (yellow arrows). (b) A STEM-iDPC image showing positions of Pb, Zr, and O atoms. Red lines connect O positions situated between Zr columns in ZrO₂ planes along the horizontal direction. The fluctuation magnitude and directional trend of the O-chain indicate both the magnitude and direction of oxygen octahedral rotation. (c) O chain characteristic in PZO single crystal lamella without a twin boundary. The oxygen octahedral rotation angle is defined in the inset as the angle between the line connecting two neighbouring oxygen ions (red line) and the horizontal reference line (yellow dashed line). (d) A rotation map of oxygen octahedra extracted from (b). The sign of O octahedra rotation angle is defined in the inset.