Evolution of bias field and offset piezoelectric coefficient in bulk lead zirconate titanate with fatigue

Hysteresis loops of the piezoelectric coefficient, d33 =f (E3), are measured on virgin and fatigued lead zirconate titanate ceramics. Four parameters are directly extracted from the measurements: internal bias field Eb, offset piezoelectric coefficient doffset, coercive field Ec, and remnant piezoelectric coefficient dr. The reduction in dr displays the decreasing switchable polarization with fatigue cycling. Eb and doffset are found to be linearly related. After thermal annealing, both offsets disappear, while the increase in Ec and the reduction in dr withstand annealing. The microscopic entities responsible for the offsets are less stable than those for reduced switching.