Fig. 2: Local structures of the crystals.
A–C The high-angle annular dark-field (HAADF) images of the pristine, Fe-doped, and Mn-doped KTN crystals, obtained along the [001]C direction at room temperature, respectively. The small and large bright points represent the A-site and B-site ions, respectively. Mappings of the polar vectors are marked by yellow arrows in (A–C). The atomic displacements are presented as vectors pointing from the center of a B-site cation to the center of its four nearest neighboring A-site cations. These atomic displacements represent the magnitudes and directions of the polar vectors for each unit-cell column. The x, y, and z directions correspond to the [100]C, [010]C, and [001]C crystallographic directions, respectively. The statistical scatterplots of the absolute value of the angle between the polar vector and the x-axis are shown in (D–F) for pristine, Fe-doped, and Mn-doped samples, respectively. G–I Distributions of shear strain exy and J–L phase of piezoresponse force microscopy (PFM) images on the (001)C faces of the pristine, Fe-doped, and Mn-doped samples, respectively. The white color in the exy distribution maps indicates the zero exy strain regions. The exx, eyy, and Rtot distributions are shown in Fig. S4.
