Surface acoustic wave (SAW) propagation in relaxor-based ferroelectric single crystals 0.93Pb(Zn 1/3 Nb 2/3)O3-0.07PbTiO3 (PZN-7%PT) poled along [011] has been analyzed theoretically. The results show that PZN-7%PT single crystals have excellent SAW properties, such as low phase velocities, very high electromechanical coupling coefficients and small power flow angles. It is also found that the SAW properties strongly depend on the propagation direction and the characteristic curves of SAW phase velocity, and the electromechanical coupling coefficients are symmetric with respect to = 90 ∘. Considering all related factors, the-cut PZN-7%PT single crystal has the best performance. Based on our results, the-cut PZN-7%PT single crystals poled along [011] are an excellent candidate for ultra-wide bandwidth low-frequency SAW devices.

The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear. In this work, we discuss the influence of temperature on two-dimensional (2D) mode coupling effect and electromechanical coupling coefficient of cylindrical [001] c -poled Mn-doped 0.24PIN–0.46PMN–0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio. The electromechanical coupling coefficient k t decreases with temperature increasing, whereas k 33 is largely invariant in a temperature range of 25 °C–55 °C. With the increase of temperature, the shift in the ‘mode dividing point’ increases the scale of the poling direction of the piezoelectric vibrator. The temperature has little effect on coupling constant Γ. At a given temperature, the coupling constant Γ of the cylindrical vibrator is slightly greater than that of the rectangular vibrator. When the temperature changes, the applicability index (M) values of the two piezoelectric vibrators are close to 1, indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.

Huang Nai-Xing(黄乃兴) a)b) , Lü Tian-Quan(吕天全) a) † , Zhang Rui(张 锐) a) ‡ , and Cao Wen-Wu(曹文武) a)c) a)