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 for a poling time (t p) of 100 sec showed a piezoelectric charge coefficient d 33 of 141.3 pC/N, an almost equivalent d 33 (141.3 pC/N) was recorded by pulse-poling in only 10 sec under a unipolar electric field of 4.0 kV/mm, 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 under any condition. Polarization-electric field (P-E) responses, and domain structure observations via scanning electron microscopy (SEM), 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.

Effect of strontium substitution on growth and piezoelectric properties of calcium magnesium silicate Ca2MgSi2O7 single crystals

“…Polar piezoelectric materials generally have a high dielectric constant and high piezoelectric constant d ij ; hence, they have been used in medical transducer and actuator devices. [2][3][4][5][6] On the other hand, nonpolar piezoelectric materials show a low dielectric constant and low d ij , but have higher phase transition temperatures. Therefore, their possible applications include gas sensors, 7) microbalance, 8) and combustion pressure sensors, 9) which operate at temperatures higher than 300 °C.…”