Evolution of piezoelectric resonance in switching current of 0.68Pb(Mg _1/3Nb_2/3)O₃-0.32PbTiO₃ ferroelectric single crystal excited by a stepwise electric field

Piezoelectric resonance current and switching current of 0.68Pb(Mg _1/3Nb_2/3)O₃-0.32PbTiO₃ (PMT-32%PT) single crystal were investigated by a stepwise electric field. As the reversely applied field increased from the coercive field to higher levels, high frequency resonance current always existed while the low frequency resonance current was replaced by a peak in the switching current gradually. This phenomenon is discussed based on a domain reversal process. The maximum switching current observed in switching current is fitted well using the equation proposed by Merz. This indicates that domain wall growth, instead of domain nucleation, plays an important role in that process.