Large-Amplitude Piezoelectric Properties of KNbO_3-Based Lead-Free Ferroelectric Ceramics

摘要

High-power piezoelectric characteristics of Mn-doped KNbO_3 (KN + MnCO_3 at x wt%, x = 0 to 0.8 wt%, KN-Mnx) ceramics are reported for the first time in this paper. The mechanical quality factor Q_m of KN-Miu ceramics at small-amplitude vibration increased with the Mn content, and the Q_m of KN-Mn0.8 ceramic reached about 820. The maximum vibration speed v_(o-p), about 2.3 ms, was obtained for KN-Mn0.8 with Q_m = 820. Q_m for large-amplitude vibration in KN-Mn0.8 and Pb(Zr, Ti)O_3 (PZT)-based ceramics (N6) decreased with increasing v_(o-p). Q_m of KN-Mn0.8 was smaller than that of N6 for small-amplitude vibration. However, for large-amplitude vibration at which v_(o-p) > 0.6 m/s, the Q_m value of KN-Mn0.8 was larger than that of N6. These results indicate that KN-based lead-free piezoelectric ceramics possess superior mechanical stability for large-amplitude vibration. This is a very good sign for high-power piezoelectric applications.