Polarization reversal and dynamic scaling of (Na0.5K0.5)NbO3 lead-free ferroelectric ceramics with double hysteresis-like loops

The polarization reversal and dynamic hysteresis of ferroelectrics specially with double hysteresis-like loops were investigated by using CuO-doped (Na0.5K0.5)NbO3 ceramics. The variation of the hysteresis area and current density clearly suggests three stages of the polarization reversal. It was found that the hysteresis behavior of the dynamics can be scaled as power law relationships apart from the second stage, where different numbers of domains can be rapidly activated. The main polarization mechanism was ascribed to the reversible domain wall motion (field amplitude Eo < 0.5Ec) and 180° domain switching (0.5Ec < Eo < Ec) for the first stage, and to the non-180° domain switching (Eo > 3.5 kV/mm) for the third stage.