(color online) (a) Image of an LDW segment. Arrows denote the geometric central plane of the domain wall, which is referred to as the origin for quantitative analysis of the dipole distortion across the domain wall area. (b) The displacements of the Zr/Ti atoms (δ_Zr/Ti) and the O atoms (δ_O) across the LDW. Positive values denote upward shifts and negative values downward shifts. (c) The spontaneous polarization . The positive values represent upward polarization and the negative values downward polarization.^[29]