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

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.