Hardening Mechanism in Lead-Free Piezoelectric Ceramics and Their Behavior Under High Power Conditions
E.A. Gurdal1, L. Zhang2, T. Tou3, M. Hajezi4, A. Safari4, K. Uchino5
1 The Pennsylvania State University, Pennsylvania, USA
2 Xi'an Jiaotong University, Xi'a, China
3 Honda Electronics Co., Toyohashi, Japan
4 Rutgers University, Piscataway, New Jersey, USA
5 ONR Global-Asia, Office of Naval Research, Tokyo, Japan
Na0.5K0.5(Nb0.97Sb0.03)O3:NKN was prepared with mixed oxides method and mixed with Yb2O3, NiO, MnO2, and CuO at 1.5 mol%. Pellets were sintered around 1100˚C for 3h in ambient atmosphere. All ceramics showed pure perovskite phase with high relative density (~99%). Doping improved both coercive (Ec) and internal bias field (Ei). Cu-doped NKN ceramics possessed the highest coercive and internal bias fields (Ec=1.23 kV/mm and Ei=0.37 kV/mm). Longer calcination time (+4h) futher improved both coercive and internal bias fields (Ec=1.70 kV/mm and Ei=0.60 kV/mm). NKN-Cu and NKN-Mn showed hard characteristics with lower dielectric loss (tanδ≤0.01) and higher mechanical quality factor (Qm≥200) when compared to Yb-doped, Ni-doped and the
base NKN ceramics. Increase in Qm and thus the hardening started above a threshold around E=0.20 kV/mm. Above 0.2 kV/mm, Ei and Qm were proportional to each other. High power behavior of several lead-free piezoelectric ceramics was also investigated. Bismuth perovskite and alkali-niobate ceramics were chosen and compared to a commercially available hard-PZT. Disk shape ceramics were continuously excited at high vibration velocity levels in radial mode. Hard lead-free ceramics were much more durable at high power conditions when compared to hard-PZT’s. Hard lead-free ceramics also possessed higher maximum vibration velocity (vmax=0.4 m/s) when compared to hard-PZT’s (vmax=0.3 m/s). This superior behavior makes lead-free piezoelectric ceramics very promising for high power applications in the future.
ACTUATOR 2014 Manuscript A1.4
Publication date: 07/04/2015
Manuscript A1.4 published in Conference Proceedings ACTUATOR 2014
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