High power characterization of (Na0.5K0.5)NbO3 based lead-free piezoelectric ceramics

Abstract

Though there is a lot of research related with lead-free piezoelectric materials, there are quite few research on high power characteristics of the lead-free piezoelectric materials. Especially under equilibrium conditions (continuous drive), high power characteristics in resonance and anti-resonance regions still remain unrevealed. This study investigates the high power characteristics of a sodium-potassium-niobate (NKN) based piezoelectric ceramic compared to hard lead-zirconate-titanate (PZT) under equilibrium conditions. High power characteristics were investigated with our novel high power piezoelectric characterization system (HiPoCS). (Na0.5K0.5)(Nb0.97Sb0.03)O3 was prepared with 1.5% mol CuO addition with the mixed–oxides method. Disk-shaped samples were sintered with the conventional sintering methods. The mechanical quality factor (Qm) at resonance (QA) did not possess degradation with the increasing vibration velocity (vrms). Accordingly, it remained constant up to 0.4m/s, which corresponds to the maximum vibration velocity (vrms measured with 20°C increase of the temperature on the nodal point). This behavior is superior when compared to hard-PZTs with their sharp decrease in QA with the increasing vibration velocity. At anti-resonance, the high power behavior trend was similar to that of at resonance. The mechanical quality factor at anti-resonance (QB) also remained constant up to the maximum vibration velocity (vmax=0.4m/s). Moreover, QA and QB were in the same order up to vmax. This trend is also distinctly different than hard-PZTs and needs to be further investigated. In conclusion, NKN ceramics are capable of possessing good high power behavior at both resonance and anti-resonance modes.