Fig. 1

Schematic of charged domain walls for tetragonal perovskite ferroelectrics. Arrows show directions of spontaneous polarization. a 180° non-ferroelastic weakly charged domain wall (WCDW). b 180° non-ferroelastic strongly charged domain wall (SCDW). c 90° ferroelastic WCDW. d 90° ferroelastic SCDW. Small deviations of WCDWs from their electro-neutral orientations (shown with dashed lines) are exaggerated. Twist in (c) and (d) schematically shows the difference in spontaneous strains between ferroelastic domains