Large Amplitude Piezoelectric Properties of KNbO3-based Lead-free Ferroelectric Ceramics
High power piezoelectric characteristics of Mn doped KNbO3 (KN+MnCO3 x wt% x=0∼0.8 wt%, KN-Mnx) ceramics were firstly reported in this paper. Mechanical quality factor, Qm, of KN-Mn x ceramics at small amplitude vibration increased with increasing Mn content and the Qm of KN-Mn0.8 ceramic reached about 820. The maximum vibration velocity, vo-p, about 2.3 m/s was obtained for KN-Mn0.8 with Qm=820. The Qm at large-amplitude vibration for KN-Mn0.8 and Pb(Zr,Ti)O3 [PZT]-based ceramics [N6] decreased with increasing the vo-p. The Qm of KN-Mn0.8 was smaller than that of N6 at the small-amplitude vibration. However, at the large amplitude vibration, vo-p>0.6 m/s, the Qm value of KN-Mn0.8 was larger than that of N6. Therefore, it was clarified that KN-based lead-free piezoelectric ceramics possess superior mechanical stability at large-amplitude vibration. This is very good sign for high power piezoelectric applications.