The effects of poling state and pores on the fracture toughness of Pb(Zr 0?95 Ti 0?05 )O 3 (PZT 95/5) ferroelectric ceramics were investigated. X-ray diffraction analysis and piezoelectric constant measurements reveal that the phase structures of PZT 95/5 ceramics change with the poling state, which significantly affects the fracture toughness. The poled PZT 95/5 ceramics demonstrate higher fracture toughness than the unpoled ceramics, and their fracture toughness significantly increases after the pressure depoling. As the porosity of ceramics increases with addition of poreformer during preparation, their fracture toughnesses all decrease accordingly either in poled state or unpoled state. The effect of pore size on the fracture toughness is subtle for the poled ceramics, but for the hydrostatic pressure depoled porous PZT 95/5 ceramics, their fracture toughness increases with the increase in pore size. A new stress model is proposed to explain the pore size effect on the fracture toughness of hydrostatic pressure depoled PZT 95/5 ceramics.

Shock-induced phase transition of ferroelectric ceramic PZT 95/5 causes elastic stiffening and depolarization, releasing stored electrostatic energy into the load circuit. We develop a model to describe the response of the PZT ferroelectric ceramic and implement it into simulation codes. The model is based on the phenomenological theory of phase transition dynamics and takes into account the effects of the self-generated intensive electrical field and stress. Connected with the discharge model and external circuit, the whole transient process of PZT ceramic depoling can be investigated. The results show the finite transition velocity of the ferroelectric phase and the double wave structure caused by phase transition. Simulated currents are compared with the results from experiments with shock pressures varying from 0.4 to 2.8 GPa.