Domain texture dependent fracture behavior in mechanically poled/depoled ferroelectric ceramics

The influence of domain texture on the fracture behavior was investigated in both the mechanically poled (MP) and the mechanically depoled (MD) PZT ceramics. Firstly, we fabricated axisymmetric domain textures in the MP and MD PZT samples subjected to a series of compressive stresses of up to 400 MPa. Then the Vickers indentation was employed to measure the fracture toughness parallel to (KIC∥) and perpendicular to (KIC⊥) the compression direction. Results show that with increasing compressive stress, KIC⊥ increases and KIC∥ decreases in both the MP and MD samples and KIC⊥ can reach 2.6-2.7 MPa m1/2 at 400 MPa. Such fracture behavior is attributed to the ferroelastic domain switching toughening mechanism in ferroelectric ceramics, and the fracture toughness is proportional to the texture-dependent switchable strain near the crack surface. The obtained results may provide a helpful guidance for improving the reliability and performance of ferroelectric capacitors.