In situ observation of electric field induced crack propagation in BaTiO3 crystals along the field direction

Electric field induced crack propagation in BaTiO3 crystals is investigated in situ using polarized light microscopy. A natural through-crack was generated by Knoop indentation and crack propagation is observed under a cyclic electric field parallel to crack direction. The crack propagates steadily along the field direction in a zigzag path and 90° domain switching always occurs before crack propagation. The shear stress caused by incompatible domain switching near the crack tip is thought to be the driving force for crack growth.