Nonlinear Behavior and High-Power Properties of (Bi,Na,Ba)TiO3 and (Sr,Ca)2NaNb5O15 Piezoelectric Ceramics

The nonlinear behaviors and high-power properties of two lead-free piezoelectric ceramics – (Bi1/2Na1/2)0.85Ba0.15Ti0.98Mn0.02O3 (BNBTM) and Sr1.9Ca0.1NaNb5O15 (SCNN) – were clarified by comparison of their mechanical characteristics using the continuous driving method. BNBTM ceramics exhibited jump phenomena with constant-voltage driving that were similar to those found in Pb(Zr,Ti)O3-based (PZT) ceramics. The jump phenomena of SCNN ceramics produced mirror-reversed images relative to those of BNBTM ceramics. Their nonlinear behaviors were caused by the soft-spring effect and hard-spring effect, respectively. Among the piezoelectric materials, SCNN ceramics possess notable elastic properties. With increasing vibration velocity, their rise in temperature was lower than that of PZT ceramics; in particular, the temperature of SCNN ceramics was lower than that of BNBTM ceramics. The quality factor of BNBTM ceramics gradually decreased and that of SCNN ceramics showed a broad peak. The degradation of the quality factor was thus limited, resulting in a gradual increase in the equivalent mechanical resistance.