Pulse-poling and characterization of (Na,K)NbO3 ceramics

Abstract

Abstract Conventional direct current (DC)-poling and three different types of pulse-poling were performed on MnO-added Na0.55K0.45NbO3 (NKN) ceramics. While NKN with DC-poling at 4.0 kV mm−1 for a poling time (t p) of 100 s showed a piezoelectric charge coefficient d 33 of 141.3 pC N−1, an almost equivalent d 33 (141.3 pC N−1) was recorded by pulse-poling in only 10 s under a unipolar electric field of 4.0 kV mm−1, with either triangular, or rectangular waveform. Especially when applying a triangular waveform, d 33 was enhanced remarkably with increasing the number of pulse cycles. In contrast, NKN ceramics poled by alternating current (AC) electric field showed a d 33 of less than 135 pC N−1 under any condition. Polarization–electric (P–E) field responses, and domain structure observations via scanning electron microscopy, showed the different poling behaviors for the various poling techniques. These results suggested that the pulse-poling method under unipolar electric field is an efficient poling procedure for NKN ceramics.