The charge-free zone model for electrically conductive cracks in dielectric and piezoelectric ceramics

The charge-free zone model for electrically conductive cracks in dielectric and piezoelectric ceramics is reviewed with the simplified constitutive equations and the regular constitutive equations and then applied to interpret the experimental results on window ceramic glass and poled lead zirconate titanate PIC 151 ceramics. A good agreement is found between the experimental results and the theoretical predictions from the charge-free zone model, which indicates that the concepts of fracture mechanics can be applied to the failure of conductive cracks in dielectric and piezoelectric ceramics.