Electrical fracture toughness for conductive cracks driven by electric fields in piezoelectric materials

Fracture of piezoelectric materials can be caused by either mechanical loads or by electric fields. It is shown in lead zirconate titanate ceramics that conductive cracks driven by electric fields can be described by the same fracture mechanics concepts used for mechanical loads, but with a much higher fracture toughness. The electrical fracture toughness G(IC)(E) = 223.7 +/- 17.0 N/m (95% confidence) is 25 times higher than the mechanical fracture toughness G(IC)(M) = 8.7 +/- 0.4 N/m (95% confidence). This is due to the greater energy dissipation that is possible under electric loading but not possible under mechanical loading in the brittle ceramics of lead zirconate titanate. (C) 2000 American Institute of Physics. [S0003-6951(00)01901-X].